Prevent duplicate pragma defines in clang

Author: anhu

wolfssl/wolfcrypt/types.h

@@ -2082,7 +2082,7 @@ WOLFSSL_API word32 CheckRunTimeSettings(void);
     #define WC_MP_TO_RADIX
 #endif
 
-#if defined(__GNUC__) && __GNUC__ > 5
+#if defined(__GNUC__) && (__GNUC__ > 5) && !defined(__clang__)
     #define PRAGMA_GCC_DIAG_PUSH _Pragma("GCC diagnostic push")
     #define PRAGMA_GCC(str) _Pragma(str)
     #define PRAGMA_GCC_DIAG_POP _Pragma("GCC diagnostic pop")