Fix GCC 4.7 (C++11) compilation.

src/x64/disasm-x64.cc

 // Copyright 2011 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 1666 matching lines @@
             value = *reinterpret_cast<uint32_t*>(data + 1);
             data += 5;
             break;
           case QUADWORD_SIZE:
             value = *reinterpret_cast<int32_t*>(data + 1);
             data += 5;
             break;
           default:
             UNREACHABLE();
         }
-        AppendToBuffer("test%c rax,0x%"V8_PTR_PREFIX"x",
+        AppendToBuffer("test%c rax,0x%" V8_PTR_PREFIX "x",
                        operand_size_code(),
                        value);
         break;
       }
       case 0xD1:  // fall through
       case 0xD3:  // fall through
       case 0xC1:
         data += ShiftInstruction(data);
         break;
       case 0xD0:  // fall through
@@ skipping 147 matching lines @@
     for (int i = 6 - static_cast<int>(pc - prev_pc); i >= 0; i--) {
       fprintf(f, "  ");
     }
     fprintf(f, "  %s\n", buffer.start());
   }
 }
 
 }  // namespace disasm
 
 #endif  // V8_TARGET_ARCH_X64