include documentation of ipcmp.

Reference: /n/atom/patch/applied/man2ipipcmp
Date: Fri Mar  7 16:20:14 CET 2014
Signed-off-by: quanstro@quanstro.net

--- /sys/man/2/ip	Fri Mar  7 16:19:38 2014
+++ /sys/man/2/ip	Fri Mar  7 16:19:39 2014
@@ -1,6 +1,6 @@
 .TH IP 2
 .SH NAME
-eipfmt, parseip, parseipmask, v4parseip, v4parsecidr, parseether, myipaddr, myetheraddr, maskip, equivip4, equivip6, defmask, isv4, v4tov6, v6tov4, nhgetv, nhgetl, nhgets, hnputv, hnputl, hnputs, ptclbsum, freeipifc, readipifc \- Internet Protocol addressing
+eipfmt, parseip, parseipmask, v4parseip, v4parsecidr, parseether, myipaddr, myetheraddr, maskip, equivip4, equivip6, ipcmp, defmask, isv4, v4tov6, v6tov4, nhgetv, nhgetl, nhgets, hnputv, hnputl, hnputs, ptclbsum, freeipifc, readipifc \- Internet Protocol addressing
 .SH SYNOPSIS
 .de PB
 .PP
@@ -34,6 +34,8 @@
 .PB
 int		equivip6(uchar *ipaddr1, uchar *ipaddr2)
 .PB
+int	ipcmp(uchar *ipaddr1, uchar *ipaddr2)
+.PB
 uchar*	defmask(uchar *ipaddr)
 .PB
 int		isv4(uchar *ipaddr)
@@ -181,6 +183,9 @@
 operates on v4 addresses,
 .I equivip6
 operates on v6 addresses.
+.I Ipcmp 
+is a macro that compares V6 addresses per 
+.IR memcmp (2)). 
 .PP
 .I Defmask
 returns the standard class A, B, or C mask for