zcip: Add environment variable for overriding log functionality

function                                             old     new   delta
bb_logenv_override                                     -      70     +70
packed_usage                                       29969   30033     +64
zcip_main                                           1426    1431      +5
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 2/0 up/down: 139/0)             Total: 139 bytes

Signed-off-by: Michel Stam <m.stam@fugro.nl>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/zcip.c b/networking/zcip.c
index 635d660..a3307c5 100644
--- a/networking/zcip.c
+++ b/networking/zcip.c
@@ -33,6 +33,9 @@
 //usage:     "\n	-l x.x.0.0	Use this range instead of 169.254"
 //usage:     "\n	-v		Verbose"
 //usage:     "\n"
+//usage:     "\n$LOGGING=none		Suppress logging"
+//usage:     "\n$LOGGING=syslog 	Log to syslog"
+//usage:     "\n"
 //usage:     "\nWith no -q, runs continuously monitoring for ARP conflicts,"
 //usage:     "\nexits only on I/O errors (link down etc)"
 
@@ -249,6 +252,8 @@
 		openlog(applet_name, 0, LOG_DAEMON);
 		logmode |= LOGMODE_SYSLOG;
 	}
+	bb_logenv_override();
+
 	{ // -l n.n.n.n
 		struct in_addr net;
 		if (inet_aton(l_opt, &net) == 0