Fix tmux not starting on an IPv6 only system.

Note that tmux will still not work if you have neither v4 nor v6.

PR:		203720
Obtained from:	https://github.com/tmux/tmux/issues/139
Sponsored by:	Absolight

sysutils/tmux/Makefile

@@ -3,7 +3,7 @@
 
 PORTNAME=	tmux
 PORTVERSION=	2.0
-PORTREVISION=	1
+PORTREVISION=	2
 CATEGORIES=	sysutils
 MASTER_SITES=	https://github.com/tmux/tmux/releases/download/${PORTVERSION}/ \
 		SF/${PORTNAME}/${PORTNAME}/${PORTNAME}-${PORTVERSION:S/a$//}

sysutils/tmux/files/patch-compat_imsg.c

@@ -0,0 +1,17 @@
+--- compat/imsg.c.orig	2015-10-14 13:20:40 UTC
++++ compat/imsg.c
+@@ -54,8 +54,12 @@ available_fds(unsigned int n)
+ 	for (i = 0; i < n; i++) {
+ 		fds[i] = -1;
+ 		if ((fds[i] = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
+-			ret = 1;
+-			break;
++			if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
++				fds[i] = socket(AF_INET6, SOCK_DGRAM, 0);
++			if (fds[i] < 0) {
++				ret = 1;
++				break;
++			}
+ 		}
+ 	}
+