xfree86: Keep a non-seat0 X server from touching VTs (#71258)

Updated patch following Hans de Goede's advice.

If -seat option is passed with a value different from seat0,
X server won't call xf86OpenConsole().

This is needed to avoid any race condition between seat0 and
non-seat0 X servers. If a non-seat0 X server opens a given VT
before a seat0 one which expects to open the same VT, one can
get an inactive systemd-logind graphical session for seat0.

This patch was first tested in a multiseat setup with multiple
video cards and works quite well.

I suppose it can also make things like DontVTSwitch and -sharevts
meaningless for non-seat0 seats, so it may fix bug #69477, too.

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=71258
       https://bugs.freedesktop.org/show_bug.cgi?id=69477 (maybe)

See also: http://lists.x.org/archives/xorg-devel/2013-October/038391.html
          https://bugzilla.redhat.com/show_bug.cgi?id=1018196

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>

hw/xfree86/common/xf86Init.c

@@ -544,7 +544,8 @@ InitOutput(ScreenInfo * pScreenInfo, int argc, char **argv)
             if (NEED_IO_ENABLED(flags))
                 want_hw_access = TRUE;
 
-            if (!(flags & HW_SKIP_CONSOLE))
+            /* Non-seat0 X servers should not open console */
+            if (!(flags & HW_SKIP_CONSOLE) && !ServerIsNotSeat0())
                 xorgHWOpenConsole = TRUE;
         }