handle LTC_NO_FAST before handling LTC_FAST

src/headers/tomcrypt_cfg.h

@@ -100,6 +100,10 @@ LTC_EXPORT int   LTC_CALL XSTRCMP(const char *s1, const char *s2);
    typedef unsigned long ulong32;
 #endif
 
+#ifdef LTC_NO_FAST
+   #undef LTC_FAST
+#endif
+
 #ifdef LTC_FAST
 #if __GNUC__ < 4 /* if the compiler does not support gnu extensions, i.e. its neither clang nor gcc nor icc */
 #error the LTC_FAST hack is only available on compilers that support __attribute__((may_alias)) - disable it for your compiler, and dont worry, it won`t buy you much anyway
@@ -128,12 +132,6 @@ typedef ulong64 ltc_mp_digit;
 typedef ulong32 ltc_mp_digit;
 #endif
 
-#ifdef LTC_NO_FAST
-   #ifdef LTC_FAST
-      #undef LTC_FAST
-   #endif
-#endif
-
 /* No asm is a quick way to disable anything "not portable" */
 #ifdef LTC_NO_ASM
    #undef ENDIAN_LITTLE