Add missing inet promise.

Index: tmux.c
--- tmux.c.orig
+++ tmux.c
@@ -334,7 +334,7 @@ main(int argc, char **argv)
 
 #ifdef __OpenBSD__
 	if (pledge("stdio rpath wpath cpath flock fattr unix getpw sendfd "
-	    "recvfd proc exec tty ps", NULL) != 0)
+	    "recvfd proc exec tty ps inet", NULL) != 0)
 		err(1, "pledge");
 #endif