[gdm] systemd: change to KillMode=mixed

[Ray Strode <halfline src gnome org>]

commit 7074f2a54124b54f8e85a19f6fecdb8232782a60
Author: Ray Strode <rstrode redhat com>
Date:   Mon Mar 30 21:53:33 2015 -0400

    systemd: change to KillMode=mixed
    
    This is like the previous commit, but a slightly better choice,
    because it's more fault tolerant; if GDM fails to kill a child,
    systemd will help out.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=747088

 data/gdm.service.in |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/data/gdm.service.in b/data/gdm.service.in
index 6608c2c..fb0ffdc 100644
--- a/data/gdm.service.in
+++ b/data/gdm.service.in
@@ -21,7 +21,7 @@ OnFailure=plymouth-quit.service
 
 [Service]
 ExecStart= sbindir@/gdm
-KillMode=process
+KillMode=mixed
 Restart=always
 IgnoreSIGPIPE=no
 BusName=org.gnome.DisplayManager