Feed Clang a pragma to ignore -Wc++11-extensions to let it build Skia on Mac.

include/core/SkPostConfig.h

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkPostConfig_DEFINED
@@ skipping 304 matching lines @@
 #endif
 
 #endif
 
 //////////////////////////////////////////////////////////////////////
 
 #ifndef SK_OVERRIDE
     #if defined(_MSC_VER)
         #define SK_OVERRIDE override
     #elif defined(__clang__) && !defined(SK_BUILD_FOR_IOS)
+        // Clang defaults to C++03 and warns about using override. Squelch that. Intentionally no
+        // push/pop here so all users of SK_OVERRIDE ignore the warning too. This is like passing
+        // -Wno-c++11-extensions, except that GCC won't die (because it won't see this pragma).
+        #pragma clang diagnostic ignored "-Wc++11-extensions"
+
         #if __has_feature(cxx_override_control)
             // Some documentation suggests we should be using __attribute__((override)),
             // but it doesn't work.
             #define SK_OVERRIDE override
         #elif defined(__has_extension)
             #if __has_extension(cxx_override_control)
                 #define SK_OVERRIDE override
             #endif
         #endif
     #else
@@ skipping 20 matching lines @@
 #else
 #define SK_SIZE_T_SPECIFIER "%zu"
 #endif
 #endif
 
 //////////////////////////////////////////////////////////////////////
 
 #ifndef SK_ALLOW_STATIC_GLOBAL_INITIALIZERS
 #define SK_ALLOW_STATIC_GLOBAL_INITIALIZERS 1
 #endif