message: mingw not happy with fs
diff: #include <string>
  #ifdef __MINGW32__
  +#include <sys/stat.h>
  +
  // need to manually define this for mingw
  extern "C" WINBASEAPI BOOL WINAPI GetPhysicallyInstalledSystemMemory(PULONGLONG);
  #endif
  @@ -224,15 +226,7 @@ void FileSystem::RemoveFile(const string &filename) {
  bool FileSystem::IsFile(const string &filename) {
  if (!filename.empty()) {
  -#ifdef __MINGW32__
  - if (_access(filename.c_str(), 0) == 0) {
  - struct _stat32 status;
  - stat(filename.c_str(), &status);
  - if (S_ISREG(status.st_mode)) {
  - return true;
  - }
  - }
  -#elifdef _WIN32
  +#if defined(_WIN32) && defined(__MINGW32__)
  if (_access(filename.c_str(), 0) == 0) {
  struct stat status;
  stat(filename.c_str(), &status);
  @@ -240,7 +234,6 @@ bool FileSystem::IsFile(const string &filename) {
  return true;
  }
  }
  -
  #else
  if (access(filename.c_str(), 0) == 0) {
  struct stat status;
  