Wrap __attribute__s in macros

code/sys/sys_local.h

@@ -61,7 +61,7 @@ void Sys_GLimpSafeInit( void );
 void Sys_GLimpInit( void );
 void Sys_PlatformInit( void );
 void Sys_PlatformExit( void );
-void Sys_SigHandler( int signal ) __attribute__ ((noreturn));
+void Sys_SigHandler( int signal ) Q_NO_RETURN;
 void Sys_ErrorDialog( const char *error );
 void Sys_AnsiColorPrint( const char *msg );