Fix build for msvc compilers.
Support static library building without public exports.
[win32] Add support for static windows build

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Merge https://github.com/vitamin-caig/libxmp

Handle BUILDING_STATIC in xmp.h in a slightly different way.

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>

Conflicts:
	include/xmp.h
	src/loaders/mmd3_load.c