[gimp] Issue #1974: and again another memory leak.

[Jehan <jehanp src gnome org>]

commit b3c9089ea2561c5d807fd5556f6750e1f0b77b22
Author: Jehan <jehan girinstud io>
Date:   Sun Aug 5 11:47:24 2018 +0200

    Issue #1974: and again another memory leak.
    
    Thanks to Massimo for reporting all these!

 app/widgets/gimpfileprocview.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/app/widgets/gimpfileprocview.c b/app/widgets/gimpfileprocview.c
index 8f0a30d4f7..554c1553e0 100644
--- a/app/widgets/gimpfileprocview.c
+++ b/app/widgets/gimpfileprocview.c
@@ -166,6 +166,7 @@ gimp_file_proc_view_new (Gimp        *gimp,
                                   COLUMN_HELP_ID,    help_id,
                                   COLUMN_FILTER,     filter,
                                   -1);
+              g_object_unref (filter);
             }
 
           for (list2 = proc->extensions_list;