Allow building libdeflate without linking to any libc functions by using
'make FREESTANDING=1'. When using such a library build, the user will
need to call libdeflate_set_memory_allocator() before anything else,
since malloc() and free() will be unavailable.
[Folded in fix from Ingvar Stepanyan to use -nostdlib, and made
freestanding_tests() check that no libs are linked to.]
Update https://github.com/ebiggers/libdeflate/issues/62
In preparation for adding custom memory allocator support, don't call
the standard memory allocation functions directly but rather wrap them
with libdeflate_malloc() and libdeflate_free().
Move the x86 and ARM-specific code into their own directories to prevent
it from cluttering up the main library. This will make it a bit easier
to add new architecture-specific code.
But to avoid complicating things too much for people who aren't using
the provided Makefile, we still just compile all .c files for all
architectures (irrelevant ones end up #ifdef'ed out), and the headers
are included explicitly for each architecture so that an
architecture-specific include path isn't needed. So, now people just
need to compile both lib/*.c and lib/*/*.c instead of only lib/*.c.
It was reported that API symbols were being "exported" from the static
library built with MSVC, causing them to remain exported after being
linked into another program. It turns out this was actually a problem
outside of MSVC as well. The solution is to always build the static and
shared libraries from different object files, where the API symbols are
exported from the shared library object files but not from the static
library object files.
Reported-by: Joergen Ibsen <ji@ibse.dk>
