Fix gyp files to allow ninja to build 64 bit on Mac.

gyp/common_conditions.gypi

 # conditions used in both common.gypi and skia.gyp in chromium
 #
 {
   'defines': [
     'SK_ALLOW_STATIC_GLOBAL_INITIALIZERS=<(skia_static_initializers)',
 #    'SK_SUPPORT_HINTING_SCALE_FACTOR',
   ],
   'conditions' : [
     [ 'skia_gpu == 1',
       {
@@ skipping 160 matching lines @@
       {
         'variables': {
           'mac_sdk%': '<!(python <(DEPTH)/tools/find_mac_sdk.py 10.6)',
         },
         'defines': [
           'SK_BUILD_FOR_MAC',
         ],
         'conditions' : [
           [ 'skia_arch_width == 64', {
             'xcode_settings': {
-              'ARCHS': 'x86_64',
+              'ARCHS': ['x86_64'],
             },
           }],
           [ 'skia_arch_width == 32', {
             'xcode_settings': {
-              'ARCHS': 'i386',
+              'ARCHS': ['i386'],
             },
           }],
           [ 'skia_warnings_as_errors', {
             'xcode_settings': {
               'OTHER_CPLUSPLUSFLAGS': [
                 '-Werror',
               ],
             },
           }],
         ],
@@ skipping 70 matching lines @@
             },
           },
           'Release': {
             'xcode_settings': {
               'GCC_OPTIMIZATION_LEVEL': '3',
             },
             'defines': [ 'NDEBUG' ],
           },
         },
         'xcode_settings': {
-          'ARCHS': 'armv6 armv7',
+          'ARCHS': ['armv6', 'armv7'],
           'CODE_SIGNING_REQUIRED': 'NO',
           'CODE_SIGN_IDENTITY[sdk=iphoneos*]': '',
           'IPHONEOS_DEPLOYMENT_TARGET': '<(ios_sdk_version)',
           'SDKROOT': 'iphoneos',
           'TARGETED_DEVICE_FAMILY': '1,2',
           'OTHER_CPLUSPLUSFLAGS': [
             '-fvisibility=hidden',
             '-fvisibility-inlines-hidden',
           ],
           'GCC_THUMB_SUPPORT': 'NO',
@@ skipping 88 matching lines @@
   'xcode_settings': {
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }
 
 # Local Variables:
 # tab-width:2
 # indent-tabs-mode:nil
 # End:
 # vim: set expandtab tabstop=2 shiftwidth=2: