Make Mac build generate both 32-bit and 64-bit code.

BUG=http://code.google.com/p/skia/issues/detail?id=524
Review URL: https://codereview.appspot.com/6022057

git-svn-id: http://skia.googlecode.com/svn/trunk/gyp@3687 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed