Implement correct OS and CC detection.

src/snapshot-common.cc

 // Copyright 2006-2008 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 29 matching lines @@
 
 static void ReserveSpaceForSnapshot(Deserializer* deserializer,
                                     const char* file_name) {
   int file_name_length = StrLength(file_name) + 10;
   Vector<char> name = Vector<char>::New(file_name_length + 1);
   OS::SNPrintF(name, "%s.size", file_name);
   FILE* fp = OS::FOpen(name.start(), "r");
   CHECK_NE(NULL, fp);
   int new_size, pointer_size, data_size, code_size, map_size, cell_size,
       property_cell_size;
-#ifdef _MSC_VER
+#if V8_CC_MSVC
   // Avoid warning about unsafe fscanf from MSVC.
   // Please note that this is only fine if %c and %s are not being used.
 #define fscanf fscanf_s
 #endif
   CHECK_EQ(1, fscanf(fp, "new %d\n", &new_size));
   CHECK_EQ(1, fscanf(fp, "pointer %d\n", &pointer_size));
   CHECK_EQ(1, fscanf(fp, "data %d\n", &data_size));
   CHECK_EQ(1, fscanf(fp, "code %d\n", &code_size));
   CHECK_EQ(1, fscanf(fp, "map %d\n", &map_size));
   CHECK_EQ(1, fscanf(fp, "cell %d\n", &cell_size));
   CHECK_EQ(1, fscanf(fp, "property cell %d\n", &property_cell_size));
-#ifdef _MSC_VER
+#if V8_CC_MSVC
 #undef fscanf
 #endif
   fclose(fp);
   deserializer->set_reservation(NEW_SPACE, new_size);
   deserializer->set_reservation(OLD_POINTER_SPACE, pointer_size);
   deserializer->set_reservation(OLD_DATA_SPACE, data_size);
   deserializer->set_reservation(CODE_SPACE, code_size);
   deserializer->set_reservation(MAP_SPACE, map_size);
   deserializer->set_reservation(CELL_SPACE, cell_size);
   deserializer->set_reservation(PROPERTY_CELL_SPACE,
@@ skipping 58 matching lines @@
   deserializer.set_reservation(MAP_SPACE, context_map_space_used_);
   deserializer.set_reservation(CELL_SPACE, context_cell_space_used_);
   deserializer.set_reservation(PROPERTY_CELL_SPACE,
                                context_property_cell_space_used_);
   deserializer.DeserializePartial(&root);
   CHECK(root->IsContext());
   return Handle<Context>(Context::cast(root));
 }
 
 } }  // namespace v8::internal