x11/xdm: Use $LOCALBASE/etc/xdm/Xservers as base for Xserver args

Hard coding Xserver args forces people to invoke xdm through init
by placing an entry in /etc/ttys when Xserver args different from
those hardcoded in rc.d/xdm are desired. Instead glean arguments
from $LOCALBASE/etc/xdm/Xservers, defaulting to the hardcoded
entry if none are found for :0.

Reviewed by:	manu
Differential Revision:	https://reviews.freebsd.org/D42097

x11/xdm/Makefile

@@ -1,6 +1,6 @@
 PORTNAME=	xdm
 PORTVERSION=	1.1.14
-PORTREVISION=	3
+PORTREVISION=	4
 CATEGORIES=	x11
 
 MAINTAINER=	x11@FreeBSD.org

x11/xdm/files/xdm.in

@@ -38,7 +38,11 @@ xdm_set_vty()
 {
 	# X views vt as starting at 01, not ttyv0
 	vtarg=`printf vt%02d $((${xdm_tty#ttyv} + 1))`
-	command_args="-server \":0 local %%LOCALBASE%%/bin/X :0 $vtarg\""
+	xserver_args=$(grep '^:0' %%LOCALBASE%%/etc/X11/xdm/Xservers)
+	if [ $? -ne 0 ]; then
+		xserver_args=":0 local %%LOCALBASE%%/bin/X :0"
+	fi
+	command_args="-server \"$xserver_args $vtarg\""
 }
 
 run_rc_command $1