Make compile with gcc 4.7 work

mojo/public/c/system/macros.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MOJO_PUBLIC_C_SYSTEM_MACROS_H_
 #define MOJO_PUBLIC_C_SYSTEM_MACROS_H_
 
 #include <stddef.h>
 
 // Annotate a variable indicating it's okay if it's unused.
@@ skipping 55 matching lines @@
 #else
 #error "Please define MOJO_ALIGNOF() for your compiler."
 #endif
 
 // Specify the alignment of a |struct|, etc.
 // Use like:
 //   struct MOJO_ALIGNAS(8) Foo { ... };
 // Unlike the C++11 |alignas()|, |alignment| must be an integer. It may not be a
 // type, nor can it be an expression like |MOJO_ALIGNOF(type)| (due to the
 // non-C++11 MSVS version).
-#if __cplusplus >= 201103L
+#if __cplusplus >= 201103L && \
+    (defined(__clang__) || (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 >= 40800))

[viettrungluu, 2014/07/29 17:47:28]

What about future versions of MSVC? This would be another thing to update.

Why is gcc 4.7 claiming to support C++11 if it in fact doesn't?

 #define MOJO_ALIGNAS(alignment) alignas(alignment)
 #elif defined(__GNUC__)
 #define MOJO_ALIGNAS(alignment) __attribute__((aligned(alignment)))
 #elif defined(_MSC_VER)
 #define MOJO_ALIGNAS(alignment) __declspec(align(alignment))
 #else
 #error "Please define MOJO_ALIGNAS() for your compiler."
 #endif
 
 #endif  // MOJO_PUBLIC_C_SYSTEM_MACROS_H_