Fix for older clang releases that lack __has_extension.

src/globals.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 98 matching lines @@
 #  define V8_CC_MINGW64 1
 # elif defined(__MINGW32__)
 #  define V8_CC_MINGW 1
 #  define V8_CC_MINGW32 1
 # elif defined(__ARMCC__) || defined(__CC_ARM)
 #  define V8_CC_RVCT 1  // ARM Realview Compiler Suite also masquerades as GCC
 # elif defined(__INTEL_COMPILER)
 #  define V8_CC_INTEL 1  // Intel C++ also masquerades as GCC 3.2.0
 # elif defined(__clang__)
 #  define V8_CC_CLANG 1  // Clang also masquerades as GCC 4.2.1
+#  ifndef __has_extension
+#   define __has_extension __has_feature  // Compatibility with older releases
+#  endif
 # endif
 #elif defined(__ARMCC__) || defined(__CC_ARM)
 # define V8_CC_RVCT 1
 #elif defined(__INTEL_COMPILER)
 # define V8_CC_INTEL 1
 #elif defined(__SUNPRO_CC) || defined(__SUNPRO_C)
 # define V8_CC_SUN 1
 #else
 # error Compiler was not detected as supported by v8
 #endif
@@ skipping 424 matching lines @@
 // the backend, so both modes are represented by the kStrictMode value.
 enum StrictModeFlag {
   kNonStrictMode,
   kStrictMode
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_GLOBALS_H_