Have Clang builders build in C++11 mode.

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_GPU=<(skia_gpu)',
     'SK_SUPPORT_OPENCL=<(skia_opencl)',
     'SK_FORCE_DISTANCEFIELD_FONTS=<(skia_force_distancefield_fonts)',
   ],
   'conditions' : [
@@ skipping 456 matching lines @@
                 'target_conditions': [
                   [ '_type == "executable"', {
                     'cflags': [ '-fPIE' ],
                     'ldflags': [ '-pie' ],
                   }],
                 ],
               }],
             ],
           }],
           [ 'skia_clang_build', {
+            'cflags_cc': [
+                # Build in C++11 mode to make sure we'll have an easy time switching.
+                '-std=c++11',
+                '-Wno-unknown-warning-option',  # Allows unknown warnings.
+                '-Wno-deprecated',              # From Qt, via debugger (older Clang).
+                '-Wno-deprecated-register',     # From Qt, via debugger (newer Clang).
+            ],
             'cflags': [
-              # Extra warnings we like but that only Clang knows about.
-              '-Wstring-conversion',
+                # Extra warnings we like but that only Clang knows about.
+                '-Wstring-conversion',
             ],
             'cflags!': [
                 '-mfpmath=sse',  # Clang doesn't need to be told this, and sometimes gets confused.
             ],
           }],
           [ 'skia_keep_frame_pointer', {
             'cflags': [ '-fno-omit-frame-pointer' ],
           }],
         ],
       },
@@ skipping 199 matching lines @@
         # add flags here (e.g. SK_SUPPORT_LEGACY_...) needed by moz2d
       ],
     }],
 
   ], # end 'conditions'
   # The Xcode SYMROOT must be at the root. See build/common.gypi in chromium for more details
   'xcode_settings': {
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }