[gimp] libgimp: actually unref the global GimpPDB and GimpPlugIn instances

[Michael Natterer <mitch src gnome org>]

commit 34f848bb690d32dc3ead864c54d666cbbac18131
Author: Michael Natterer <mitch gimp org>
Date:   Thu Sep 5 12:22:04 2019 +0200

    libgimp: actually unref the global GimpPDB and GimpPlugIn instances
    
    in gimp_close().

 libgimp/gimp.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/libgimp/gimp.c b/libgimp/gimp.c
index 1b11d7df42..045c7c734d 100644
--- a/libgimp/gimp.c
+++ b/libgimp/gimp.c
@@ -917,6 +917,9 @@ gimp_close (void)
     _gimp_debug_stop ();
 
   _gimp_plug_in_quit (PLUG_IN);
+
+  g_clear_object (&PDB);
+  g_clear_object (&PLUG_IN);
 }
 
 static void