Add yasm flags for 64-bit mac builds

Add yasm flags for 64-bit mac builds. 

BUG=150760, 150980
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=157771

[Cătălin Badea, 2012-09-19 13:41:20]

This patch addresses 64-bit mac build issues related to third_party/libvpx and
media/yuv_converter 64-bit. Please review.

[Mark Mentovai, 2012-09-19 13:42:41]

https://codereview.chromium.org/10952023/diff/2001/third_party/yasm/README.ch...
File third_party/yasm/README.chromium (right):

https://codereview.chromium.org/10952023/diff/2001/third_party/yasm/README.ch...
third_party/yasm/README.chromium:18: - yasm.gyp was modified to include flags
for 64-bit mac builds.
yasm.gyp is our own file, so this isn’t a “local modification.”

[Cătălin Badea, 2012-09-19 13:48:02]

I removed the readme modifications from the patch set.

[Mark Mentovai, 2012-09-19 13:50:53]

https://codereview.chromium.org/10952023/diff/6001/third_party/yasm/yasm_comp...
File third_party/yasm/yasm_compile.gypi (right):

https://codereview.chromium.org/10952023/diff/6001/third_party/yasm/yasm_comp...
third_party/yasm/yasm_compile.gypi:61: '-m', 'amd64', # yasm uses 'amd64' as
flag for the 64-bit instruction set.
80 characters.

I actually don’t think the comment is necessary at all.

[Cătălin Badea, 2012-09-19 13:56:24]

I removed the comment.

[Cătălin Badea, 2012-09-20 08:24:12]

Should I also ping an owner from src/media/ as this patch affects the build
process for some targets in src/media?

[Mark Mentovai, 2012-09-20 12:27:50]

LGTM. Additional reviews are at your own discretion.

[commit-bot: I haz the power, 2012-09-20 12:35:55]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/badea@adobe.com/10952023/10001

[commit-bot: I haz the power, 2012-09-20 15:27:17]

Change committed as 157771