replaced mpd_noreturn by G_GNUC_NORETURN

We want to remove gcc.h eventually. This takes care of all the
G_GNUC_NORETURN macros.

src/log.c

@@ -182,7 +182,7 @@ log_func(DEBUG, G_LOG_LEVEL_DEBUG)
 
 #undef log_func
 
-mpd_printf mpd_noreturn void FATAL(const char *fmt, ...)
+mpd_printf G_GNUC_NORETURN void FATAL(const char *fmt, ...)
 {
 	va_list args;
 	va_start(args, fmt);