don't pass argc in getopt32, it's superfluous

(add/remove: 0/0 grow/shrink: 12/131 up/down: 91/-727) Total: -636 bytes
   text    data     bss     dec     hex filename
 773469    1058   11092  785619   bfcd3 busybox_old
 772644    1058   11092  784794   bf99a busybox_unstripped

diff --git a/networking/ipcalc.c b/networking/ipcalc.c
index 3f99b75..7597043 100644
--- a/networking/ipcalc.c
+++ b/networking/ipcalc.c
@@ -87,7 +87,7 @@
 #if ENABLE_FEATURE_IPCALC_LONG_OPTIONS
 	applet_long_options = ipcalc_longopts;
 #endif
-	opt = getopt32(argc, argv, "mbn" USE_FEATURE_IPCALC_FANCY("phs"));
+	opt = getopt32(argv, "mbn" USE_FEATURE_IPCALC_FANCY("phs"));
 	argc -= optind;
 	argv += optind;
 	if (opt & (BROADCAST | NETWORK | NETPREFIX)) {