Makefile.mk: portable Makefile.m32

Update bare GNU Make `Makefile.m32` to:

- Move objects into a subdirectory.
- Add support for MS-DOS. Tested with DJGPP.
- Add support for Watt-32 (on MS-DOS).
- Add support for AmigaOS.
- Rename `Makefile.m32` to `Makefile.mk`
- Replace `ARCH` with `TRIPLET`.
- Build `tool_hugehelp.c` proper (when tools are available).
- Drop MS-DOS compatibility macro `USE_ZLIB` (replaced by `HAVE_LIBZ`)
- Add support for `ZLIB_LIBS` to override `-lz`.
- Omit object files when building examples.
- Default `CC` to `gcc` once again, for convenience. (Caveat: compiler
  name `cc` cannot be set now.)
- Set `-DCURL_NO_OLDIES` for examples, like autotools does.
- Delete `makefile.dj` files. Notice the configuration details and
  defaults are not retained with the new method.
- Delete `makefile.amiga` files. A successful build needs a few custom
  options. We're also not retaining all build details from the existing
  Amiga make files.
- Rename `Makefile.m32` to `Makefile.mk` to reflect that they are not
  Windows/MinGW32-specific anymore.
- Add support for new `CFG` options: `-map`, `-debug`, `-trackmem`
- Set `-DNDEBUG` by default.
- Allow using `-DOS=...` in all `lib/config-*.h` headers, syncing this
  with `config-win32.h`.
- Look for zlib parts in `ZLIB_PATH/include` and `ZLIB_PATH/lib`
  instead of bare `ZLIB_PATH`.

Note that existing build configurations for MS-DOS and AmigaOS likely
become incompatible with this change.

Example AmigaOS configuration:
```
export CROSSPREFIX=/opt/amiga/bin/m68k-amigaos-
export CC=gcc
export CPPFLAGS='-DHAVE_PROTO_BSDSOCKET_H'
export CFLAGS='-mcrt=clib2'
export LDFLAGS="${CFLAGS}"
export LIBS='-lnet -lm'
make -C lib -f Makefile.mk
make -C src -f Makefile.mk
```

Example MS-DOS configuration:
```
export CROSSPREFIX=/opt/djgpp/bin/i586-pc-msdosdjgpp-
export WATT_PATH=/opt/djgpp/net/watt
export ZLIB_PATH=/opt/djgpp
export OPENSSL_PATH=/opt/djgpp
export OPENSSL_LIBS='-lssl -lcrypt'
export CFG=-zlib-ssl
make -C lib -f Makefile.mk
make -C src -f Makefile.mk
```

Closes #9764

2 files changed, 0 insertions, 240 deletions

diff --git a/packages/DOS/README b/packages/DOS/README
deleted file mode 100644
index 8336efa41..000000000
--- a/packages/DOS/README
+++ /dev/null
@@ -1,17 +0,0 @@
-Gisle Vanem made curl build fine on DOS (and MinGW) with djgpp, OpenSSL and his
-Watt-32 stack.
-
-'make -f Makefile.dist djgpp' in the root curl dir should build it fine.
-Or enter 'lib' and do a 'make -f Makefile.dj clean all' to first delete
-'lib/curl_config.h' which is possibly from a previous incompatible Windows-build.
-
-Note 1: djgpp 2.04 beta has a sscanf() bug so the URL parsing isn't
-        done properly. Use djgpp 2.03 until they fix it.
-
-Note 2: Compile Watt-32 (and OpenSSL) with the same version of djgpp.
-        Otherwise things go wrong because things like FS-extensions and
-        errnos have been changed between releases.
-
-Note 3: Several 'USE_x' variables in 'common.dj' are on the 'USE_x ?= 0'
-        form (conditional variable assignment). So one can build like this:
-          c:\curl\lib> make -f makefile.dj USE_OPENSSL=1 USE_ZLIB=1 clean all
diff --git a/packages/DOS/common.dj b/packages/DOS/common.dj
deleted file mode 100644
index b181e8215..000000000
--- a/packages/DOS/common.dj
+++ /dev/null
@@ -1,223 +0,0 @@
-#***************************************************************************
-#                                  _   _ ____  _
-#  Project                     ___| | | |  _ \| |
-#                             / __| | | | |_) | |
-#                            | (__| |_| |  _ <| |___
-#                             \___|\___/|_| \_\_____|
-#
-# Copyright (C) 1998 - 2022, Daniel Stenberg, <daniel@haxx.se>, et al.
-#
-# This software is licensed as described in the file COPYING, which
-# you should have received as part of this distribution. The terms
-# are also available at https://curl.se/docs/copyright.html.
-#
-# You may opt to use, copy, modify, merge, publish, distribute and/or sell
-# copies of the Software, and permit persons to whom the Software is
-# furnished to do so, under the terms of the COPYING file.
-#
-# This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
-# KIND, either express or implied.
-#
-# SPDX-License-Identifier: curl
-#
-###########################################################################
-#
-# Common defines for curl (djgpp/Watt-32)
-#
-# Assumes you've unpacked curl with long-file names
-# I.e use "set LFN=y" before untaring on Win9x/XP.
-# Requires sed, rm and the usual stuff.
-#
-# Define TOPDIR before including this file.
-
-MAKEFILE = Makefile.dj
-OBJ_DIR = djgpp
-
-#
-# Find out if using a Unix-like shell or a DOS command interpreter
-#
-ifneq ($(findstring COMMAND.COM,$(SHELL)),COMMAND.COM)
-  ifneq ($(findstring CMD.EXE,$(SHELL)),CMD.EXE)
-    ifneq ($(findstring 4DOS.COM,$(SHELL)),4DOS.COM)
-      IS_UNIX_SHELL = 1
-    endif
-  endif
-endif
-
-#
-# Define shell dependent commands and vars
-#
-ifeq ($(IS_UNIX_SHELL),1)
-  COPY   = cp -f
-  DELETE = rm -f
-  MKDIR  = mkdir
-  RMDIR  = rm -f -r
-  DS     = /
-else
-  COPY   = copy
-  DELETE = del
-  MKDIR  = mkdir
-  RMDIR  = rmdir
-  DS     = \$(NOTHING)
-endif
-
-ifeq ($(OS),Windows_NT)
-  #
-  # Windows hosted djgpp cross compiler. Get it from:
-  #   https://github.com/andrewwutw/build-djgpp/releases
-  #
-  DJ_PREFIX ?= c:/some-path/djgpp/bin/i586-pc-msdosdjgpp-
-  CC = $(DJ_PREFIX)gcc
-
-else
-  #
-  # The normal djgpp 'gcc' for MSDOS.
-  #
-  CC = gcc
-endif
-
-#
-# OpenSSL is available from www.openssl.org and builds okay
-# with djgpp/Watt-32. Set to 0 if you don't need https URLs
-# (reduces curl.exe with approx 700 kB)
-#
-USE_OPENSSL ?= 0
-
-#
-# Use zlib for contents encoding. Needed for 'USE_OPENSSL=1' too.
-#
-USE_ZLIB ?= 0
-
-#
-# Use libidn for international domain names
-#
-USE_IDNA ?= 0
-
-#
-# Use Watt-32 IPv6 stack (only IPv6 name resolution working at the moment)
-#
-USE_IPV6 ?= 0
-
-#
-# Use C-Ares resolver library
-#
-USE_ARES ?= 0
-
-#
-# Enable debug code in libcurl/curl
-#
-USE_DEBUG ?= 0
-
-#
-# Enable memory tracking code in libcurl/curl
-#
-USE_CURLDEBUG ?= 0
-
-#
-# Generate a .map file in 'link_EXE' macro
-#
-MAKE_MAP_FILE ?= 0
-
-default: all
-
-#
-# Root directory for Waterloo tcp/ip etc. Change to suite.
-# WATT_ROOT should be set during Watt-32 install.
-#
-WATT32_ROOT   = $(realpath $(WATT_ROOT))
-OPENSSL_ROOT ?= $(TOPDIR)/../crypto/OpenSSL
-ZLIB_ROOT    ?= e:/djgpp/contrib/zlib
-LIBIDN_ROOT  ?= $(TOPDIR)/../IDN/libidn
-ARES_ROOT    ?= $(TOPDIR)/../DNS/c-ares
-
-CFLAGS = -g -O2 -I. -I$(TOPDIR)/include -I$(TOPDIR)/lib \
-         -I$(WATT32_ROOT)/inc -Wall -DHAVE_CONFIG_H
-
-ifeq ($(USE_OPENSSL),1)
-  CFLAGS += -DUSE_OPENSSL -I$(OPENSSL_ROOT)/include
-
-  #
-  # Squelch the warnings on deprecated functions.
-  #
-  CFLAGS += -DOPENSSL_SUPPRESS_DEPRECATED
-
-  #
-  # Use some of these too?
-  #
-  # CFLAGS += -DUSE_TLS_SRP=1                    \
-  #           -DHAVE_ENGINE_LOAD_BUILTIN_ENGINES \
-  #           -DHAVE_SSLV2_CLIENT_METHOD         \
-  #           -DOPENSSL_NO_DEPRECATED
-
-  #
-  # 'libcomm.a' is normally 'libcommon.a'. But to keep it 8+3 clean, it's
-  # shortened to 'libcomm.a'. The official OpenSSL build was recently changed
-  # and this "Common" library was added for several of the Crypto Providers.
-  #
-  OPENSSL_LIBS = $(OPENSSL_ROOT)/lib/libssl.a   \
-                 $(OPENSSL_ROOT)/lib/libcrypt.a \
-                 $(OPENSSL_ROOT)/lib/libcomm.a
-endif
-
-ifeq ($(USE_ZLIB),1)
-  CFLAGS += -DHAVE_LIBZ -I$(ZLIB_ROOT)
-endif
-
-ifeq ($(USE_IPV6),1)
-  CFLAGS += -DENABLE_IPV6
-endif
-
-ifeq ($(USE_ARES),1)
-  CFLAGS += -DUSE_ARES -I$(ARES_ROOT)/include
-endif
-
-ifeq ($(USE_IDNA),1)
-  CFLAGS += -DHAVE_LIBIDN -I$(LIBIDN_ROOT)/lib
-endif
-
-ifeq ($(USE_DEBUG),1)
-  CFLAGS += -DDEBUG=1 -DDEBUGBUILD
-endif
-
-ifeq ($(USE_CURLDEBUG),1)
-  CFLAGS += -DCURLDEBUG
-endif
-
-$(OBJ_DIR):
-	$(MKDIR) $(OBJ_DIR)
-
-$(OBJ_DIR)/%.o: %.c
-	$(CC) $(CFLAGS) -o $@ -c $<
-	@echo
-
-#
-# Link-EXE macro:
-#   $(1): the .exe
-#   $(2): the .o-files and libraries
-#
-ifeq ($(MAKE_MAP_FILE),1)
-  define link_EXE
-    $(CC) -o $(1) $(LDFLAGS) -Wl,--print-map,--sort-common $(2) > $(1:.exe=.map)
-  endef
-else
-  define link_EXE
-    $(CC) $(LDFLAGS) -o $(1) $(2)
-  endef
-endif
-
-$(TOPDIR)/docs/curl.1: $(wildcard $(TOPDIR)/docs/cmdline-opts/*.d)
-	cd $(TOPDIR)/docs/cmdline-opts; \
-	perl gen.pl mainpage > ../$(TOPDIR)/docs/curl.1
-
-DEP_REPLACE = sed -e 's@\(.*\)\.o: @\n$$(OBJ_DIR)\/\1.o: @' \
-                  -e 's@$(ARES_ROOT)@$$(ARES_ROOT)@g'       \
-                  -e 's@$(OPENSSL_ROOT)@$$(OPENSSL_ROOT)@g' \
-                  -e 's@$(WATT32_ROOT)@$$(WATT32_ROOT)@g'   \
-                  -e 's@$(ZLIB_ROOT)@$$(ZLIB_ROOT)@g'
-
-#
-# One may have to do 'make -f Makefile.dj clean' first in case
-# a foreign 'curl_config.h' is making trouble.
-#
-depend: $(DEPEND_PREREQ) $(MAKEFILE)
-	$(CC) -MM $(CFLAGS) $(CSOURCES) | $(DEP_REPLACE) > depend.dj