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@3687 2bbb7eff-a529-9590-31e7-b0007b416f81

gyp/common_conditions.gypi

@@ -132,6 +132,7 @@
 # trying to get this to work, but it needs clang I think...
 #          'WARNING_CFLAGS': '-Wexit-time-destructors',
           'CLANG_WARN_CXX0X_EXTENSIONS': 'NO',
+          'ARCHS': '$(ARCHS_STANDARD_32_64_BIT)',
         },
       },
     ],