configure: add -fPIC to CFLAGS on Haiku.

Tat forces *all* uses of the C compiler, whether it's being used in
configure-script tests or used to compile tcpdump, to gave -fPIC, which
is necessary on Haiku in order for linking to work.  Otherwise,
configure script tests that involve linking will fail.

1 files changed, 23 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 8efa665c..940979fe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -103,6 +103,29 @@ AC_SUBST(LIBS_PRIVATE)
 
 AC_CANONICAL_HOST
 
+case "$host_os" in
+
+haiku*)
+	#
+	# On Haiku, all executables are built as shared objects,
+	# and must have their code build as PIC.  This also
+	# applies to code in static libraries, as well as
+	# shared libraries, as executables may be linked
+	# with that code.
+	#
+	# At least some versions of Haiku's GCC default to PIC,
+	# with a -fno-pic option for cases where that's not desired.
+	#
+	# Clang hasn't been modified in that fashion, so Clang
+	# builds of tcpdump fail.  This is Haiku bug 18258.
+	#
+	# Force the use of -fPIC (even for GCC; adding -fPIC for GCC
+	# won't break anything).
+	#
+	CFLAGS="$CFLAGS -fPIC"
+	;;
+esac
+
 AC_LBL_C_INIT_BEFORE_CC(V_CCOPT, V_INCLS)
 #
 # We require C99 or later.