[gn] Enable stricter build flags

src/mips/constants-mips.h

 // Copyright 2012 the V8 project 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  V8_MIPS_CONSTANTS_H_
 #define  V8_MIPS_CONSTANTS_H_
 #include "src/globals.h"
 // UNIMPLEMENTED_ macro for MIPS.
 #ifdef DEBUG
 #define UNIMPLEMENTED_MIPS()                                                  \
@@ skipping 104 matching lines @@
 const uint32_t kMipsSwlOffset = 3;
 #elif defined(V8_TARGET_BIG_ENDIAN)
 const uint32_t kMipsLwrOffset = 3;
 const uint32_t kMipsLwlOffset = 0;
 const uint32_t kMipsSwrOffset = 3;
 const uint32_t kMipsSwlOffset = 0;
 #else
 #error Unknown endianness
 #endif
 
+#ifndef __STDC_FORMAT_MACROS
 #define __STDC_FORMAT_MACROS
+#endif
 #include <inttypes.h>
 
 // Defines constants and accessor classes to assemble, disassemble and
 // simulate MIPS32 instructions.
 //
 // See: MIPS32 Architecture For Programmers
 //      Volume II: The MIPS32 Instruction Set
 // Try www.cs.cornell.edu/courses/cs3410/2008fa/MIPS_Vol2.pdf.
 
 namespace v8 {
@@ skipping 1210 matching lines @@
       }
       break;
     default:
       return false;
   }
 }
 }  // namespace internal
 }  // namespace v8
 
 #endif    // #ifndef V8_MIPS_CONSTANTS_H_