[glib/wip/mutexes] Revert "Drop an unused variable"

[Ryan Lortie <ryanl src gnome org>]

commit 833adbcc012dc1c1596acc3596d78e90a3cbf641
Author: Ryan Lortie <desrt desrt ca>
Date:   Mon Sep 19 13:51:07 2011 -0400

    Revert "Drop an unused variable"
    
    This reverts commit c7f9cd17d446938aaf4126e0753302676f66fd22.
    
    The old macros in gthread.h used this variable, so it must remain in
    place to keep ABI compatibility.

 glib/gthread.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/glib/gthread.c b/glib/gthread.c
index 64bd566..213540d 100644
--- a/glib/gthread.c
+++ b/glib/gthread.c
@@ -288,6 +288,7 @@ guint64        (*g_thread_gettime) (void) = gettime;
 /* Global Variables {{{1 -------------------------------------------------- */
 
 static GSystemThread zero_thread; /* This is initialized to all zero */
+gboolean g_thread_use_default_impl = TRUE;
 
 /**
  * g_thread_supported: