Actually Don't define GLIB_COMPILATION in libgthread

Last commit was wrong, fixing it up

gthread/Makefile.am

@@ -4,7 +4,6 @@ include $(top_srcdir)/Makefile.decl
 AM_CPPFLAGS = 				\
 	$(glib_INCLUDES) 		\
 	-DG_LOG_DOMAIN=\"GThread\" 	\
-	-DGLIB_COMPILATION		\
 	@GTHREAD_COMPILE_IMPL_DEFINES@ 	\
 	@GLIB_DEBUG_FLAGS@
 

gthread/gthread-impl.c

@@ -36,9 +36,13 @@
 void
 g_thread_init (gpointer init)
 {
+  if (init != NULL)
+    g_warning ("GThread system no longer supports custom thread implementations.");
 }
 
 void
 g_thread_init_with_errorcheck_mutexes (gpointer vtable)
 {
+  g_assert (vtable == NULL);
+  g_warning ("GThread system no longer supports errorcheck mutexes.");
 }