Meant to handle symbols exported from the core, but we just
pregenerate the dynamic section instead.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

The old way of specifying functions that need to be run before/after a
main function has never worked for ELF modules. Instead, the only way
to get similiar behaviour was by using the MODULE_INIT() and
MODULE_EXIT() macros, but no one seems to have bothered converting the
old __constructor users over. Anyway, the old way is superior because
it allows multiple functions be specified. Delete the MODULE_* macros
as there's only one user of them in the entire tree.

We can also get rid of the UNKNOWN_MODULE constant because now a
module doesn't need a __module_init_ptr symbol to be classed as a
library - if a module isn't an executable, it's a library, there's no
such thing as an unknown type.

It's no longer necessary to explicitly call
__syslinux_get_ipappend_strings() from ldlinux.c because the
__constructor tag on the version in com32/lib/syslinux will take care
of invoking it before ldlinux.c32's main() is executed.

Also, since we've refactored unload_module() to now run a module's
destructors let's minimise the number of callers by deleting
load_library() and unload_library(), which were only called by the
test module in com32/elflink.

Signed-off-by: Matt Fleming <matt.fleming@intel.com>

The ELF file format uses DT_NEEDED entries in the dynamic section to
name any shared library dependencies. Instead of rolling our own
dependency logic via the modules.dep file and elf_gen_dep.sh script
use the DT_NEEDED entries.

Signed-off-by: Matt Fleming <matt.fleming@linux.intel.com>

ldlinux now contains all the code necessary to load and execute
modules, none is contained in the core.

This change also allows us to change the spawn_load() prototype and to
push the job of processing arguments to executable functions (e.g. the
contents of char *argv[] as passed to a module's main function) into
ldlinux/execute.c instead of doing it in spawn_load(). Moving it into
ldlinux/ makes sense because the only core user of spawn_load() is
load_env32() and we don't require any sort of argument processing in
that path.

Signed-off-by: Matt Fleming <matt.fleming@linux.intel.com>

also make sure the compiling passed