More robust Xorg autoconfiguration

Tolerate Xorg -configure reporting a problem with multiple cards per
device by instead heuristically checking that the generated xorg.conf
is correct via trailing empty line detection.

doc/changelog.txt

@@ -5,6 +5,7 @@
   * Xorg server 1.13
 
   * Added "gentoo=xkms" boot parameter for forcing X modesetting driver
+  * More robust Xorg autoconfiguration
 
   * Added UFRaw, a RAW images viewer and converter
   * Added proxychains, a heterogeneous chaining proxyfier

src/etc/init.d/xconfig

@@ -85,7 +85,8 @@ start() {
         fi
         umount ${xorgdrv}
 
-        if [ -e ${xorgdir}/xorg.conf.new ]  &&  ! grep -q 'Configuration failed' ${xorglog}; then
+        # Empty last line means no section writing was stopped in the middle
+        if [ -e ${xorgdir}/xorg.conf.new ]  &&  [ "`tail -1 ${xorgdir}/xorg.conf.new`" = "" ]; then
             mv ${xorgdir}/xorg.conf.new ${xorgdir}/xorg.conf
 
             # Turn off text cursor on vt3 (cf. xserverrc)