[libgda] Don't return a NULL for a gboolean.

[Murray Cumming <murrayc src gnome org>]

commit caeeb40461ed6950b9c1adc2d036ee6a81264277
Author: Murray Cumming <murrayc murrayc com>
Date:   Tue Oct 27 11:46:45 2015 +0100

    Don't return a NULL for a gboolean.

 libgda/thread-wrapper/gda-worker.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/libgda/thread-wrapper/gda-worker.c b/libgda/thread-wrapper/gda-worker.c
index 2bd72a1..803a21a 100644
--- a/libgda/thread-wrapper/gda-worker.c
+++ b/libgda/thread-wrapper/gda-worker.c
@@ -1087,7 +1087,7 @@ gda_worker_wait_job (GdaWorker *worker, GdaWorkerFunc func, gpointer data, GDest
 gboolean
 gda_worker_thread_is_worker (GdaWorker *worker)
 {
-       g_return_val_if_fail (worker, NULL);
+       g_return_val_if_fail (worker, FALSE);
        return worker->worker_thread == g_thread_self () ? TRUE : FALSE;
 }