[gdm] configure: expand PID file

[Ray Strode <halfline src gnome org>]

commit 98289319a1fe4fea29478d2165f630f4f3ed8a61
Author: Luca Bruno <lucabru src gnome org>
Date:   Tue Apr 15 08:31:14 2014 -0400

    configure: expand PID file
    
    This prevents the literal "${prefix}" from getting written.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=725761

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 10bb838..72b16fe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1343,7 +1343,7 @@ else
    GDM_PID_FILE=$GDM_RUN_DIR/gdm.pid
 fi
 
-AC_SUBST(GDM_PID_FILE)
+AS_AC_EXPAND(GDM_PID_FILE, "$GDM_PID_FILE")
 AC_DEFINE_UNQUOTED(GDM_PID_FILE, "$GDM_PID_FILE", [pid file])
 
 dnl ---------------------------------------------------------------------------