Fix null deref in quit when loading corrupted machos ##bin

Author: radare

libr/bin/format/mach0/mach0.c

@@ -2057,10 +2057,12 @@ void *MACH0_(mach0_free)(struct MACH0_(obj_t) *mo) {
 	}
 
 	size_t i;
-	for (i = 0; !mo->symbols[i].last; i++) {
-		free (mo->symbols[i].name);
+	if (mo->symbols) {
+		for (i = 0; !mo->symbols[i].last; i++) {
+			free (mo->symbols[i].name);
+		}
+		free (mo->symbols);
 	}
-	free (mo->symbols);
 	free (mo->segs);
 	free (mo->sects);
 	free (mo->symtab);