Don't use strtok_s for mingw builds

src/processor/tokenize.cc

 // Copyright (c) 2010, Google Inc.
 // 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
@@ skipping 18 matching lines @@
 
 #include <string.h>
 
 #include <string>
 #include <vector>
 
 #include "common/using_std_string.h"
 
 namespace google_breakpad {
 
-#ifdef _WIN32
+#ifdef _MSC_VER
 #define strtok_r strtok_s
 #endif
 
 using std::vector;
 
 bool Tokenize(char *line,
               const char *separators,
               int max_tokens,
               vector<char*> *tokens) {
   tokens->clear();
@@ skipping 20 matching lines @@
 }
 
 void StringToVector(const string &str, vector<char> &vec) {
   vec.resize(str.length() + 1);
   std::copy(str.begin(), str.end(),
             vec.begin());
   vec[str.length()] = '\0';
 }
 
 } // namespace google_breakpad