[gdm] gdm-{wayland,x}-session: fix segfault if run with no arguments

[Ray Strode <halfline src gnome org>]

commit 5926f234b5849e21424383f28ea23f3844991402
Author: Ray Strode <rstrode redhat com>
Date:   Thu Aug 25 14:40:09 2016 -0400

    gdm-{wayland,x}-session: fix segfault if run with no arguments
    
    Right now we crash on clean up paths if the programs are invoked wrong.
    
    This commit fixes that.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=770561

 daemon/gdm-wayland-session.c |    8 +++++---
 daemon/gdm-x-session.c       |    8 +++++---
 2 files changed, 10 insertions(+), 6 deletions(-)
---
diff --git a/daemon/gdm-wayland-session.c b/daemon/gdm-wayland-session.c
index b648e9d..94f49e1 100644
--- a/daemon/gdm-wayland-session.c
+++ b/daemon/gdm-wayland-session.c
@@ -545,9 +545,11 @@ main (int    argc,
         }
 
 out:
-        signal_subprocesses (state);
-        wait_on_subprocesses (state);
-        clear_state (&state);
+        if (state != NULL) {
+                signal_subprocesses (state);
+                wait_on_subprocesses (state);
+                clear_state (&state);
+        }
 
         return exit_status;
 }
diff --git a/daemon/gdm-x-session.c b/daemon/gdm-x-session.c
index 88fe96f..3b2fcef 100644
--- a/daemon/gdm-x-session.c
+++ b/daemon/gdm-x-session.c
@@ -921,9 +921,11 @@ main (int    argc,
         }
 
 out:
-        signal_subprocesses (state);
-        wait_on_subprocesses (state);
-        clear_state (&state);
+        if (state != NULL) {
+                signal_subprocesses (state);
+                wait_on_subprocesses (state);
+                clear_state (&state);
+        }
 
         return exit_status;
 }