Streamline SIMD targets in media.gyp

Prevents duplicates of the media_sse and yuv_convert targets from
ending up in both media and media_unittests during shared builds.
- Removes the yuv_convert target since everyone who uses it already
uses media.
- Merges differ_block_sse2 and yuv_convert_simd_x86 into media_sse2.
- Moves assembly into media_asm.
- Moves incorrect mmx bundling from sse2 to new media_mmx target.
- Introduces EXPORT macro to x86inc.asm
- Introduces yasm_includes for non-.asm files in yasm_compile.gypi.
- Fixes missing const on yuv constants table.

TEST=compiles, all unittests pass.,,

Review URL:

Cr-Mirrored-Commit: 14b45ec2315b8f30607b6583b5dd762958ca7ebf
1 file changed
tree: 493a9038fb459ccde03af5dc459c701c6cb77b0a
  1. README.chromium
  2. source/
  3. yasm.gyp
  4. yasm_compile.gypi