a few more GCC-isms removed

text    data     bss     dec     hex filename
 824641     458    6956  832055   cb237 busybox_old
 824631     458    6956  832045   cb22d busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

coreutils/logname.c

@@ -27,7 +27,7 @@
 int logname_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int logname_main(int argc, char **argv UNUSED_PARAM)
 {
-	char buf[128];
+	char buf[64];
 
 	if (argc > 1) {
 		bb_show_usage();