[gdm] Define the GDM_USERNAME if not defined

[William Jon McCann <mccann src gnome org>]

commit eb2451f06226cb57e40c28b96cca618137995ad5
Author: William Jon McCann <jmccann redhat com>
Date:   Wed Jun 9 20:48:35 2010 -0400

    Define the GDM_USERNAME if not defined
    
    Useful for copy paste building.

 gui/simple-greeter/gdm-user-manager.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/gui/simple-greeter/gdm-user-manager.c b/gui/simple-greeter/gdm-user-manager.c
index 52d2a7a..a91b999 100644
--- a/gui/simple-greeter/gdm-user-manager.c
+++ b/gui/simple-greeter/gdm-user-manager.c
@@ -74,6 +74,10 @@
 #define DEFAULT_GLOBAL_FACE_DIR DATADIR "/faces"
 #define DEFAULT_USER_ICON       "avatar-default"
 
+#ifndef GDM_USERNAME
+#define GDM_USERNAME "gdm"
+#endif
+
 struct GdmUserManagerPrivate
 {
         GHashTable            *users_by_name;