Fix GNUC check on Windows (2nd attempt)

code/Common/DefaultIOStream.cpp

@@ -63,7 +63,7 @@ inline int select_fseek(FILE *file, int64_t offset, int origin) {
 
 
 
-#if defined _WIN32 && !defined __GNUC__ && __MSVCRT_VERSION__ >= 0x0601
+#if defined _WIN32 && (!defined __GNUC__ || !defined __CLANG__ && __MSVCRT_VERSION__ >= 0x0601)
 template <>
 inline size_t select_ftell<8>(FILE *file) {
     return (size_t)::_ftelli64(file);
@@ -74,7 +74,7 @@ inline int select_fseek<8>(FILE *file, int64_t offset, int origin) {
     return ::_fseeki64(file, offset, origin);
 }
 
-#endif // #if defined _WIN32 && !defined __GNUC__ && __MSVCRT_VERSION__ >= 0x0601
+#endif
 
 } // namespace
 
@@ -149,7 +149,7 @@ size_t DefaultIOStream::FileSize() const {
         //
         // See here for details:
         // https://www.securecoding.cert.org/confluence/display/seccode/FIO19-C.+Do+not+use+fseek()+and+ftell()+to+compute+the+size+of+a+regular+file
-#if defined _WIN32 && !defined __GNUC__ && __MSVCRT_VERSION__ >= 0x0601
+#if defined _WIN32 && (!defined __GNUC__ || !defined __CLANG__ && __MSVCRT_VERSION__ >= 0x0601)
         struct __stat64 fileStat;
         //using fileno + fstat avoids having to handle the filename
         int err = _fstat64(_fileno(mFile), &fileStat);