[mutter] monitor-config-migration: Fix a minor leak when parsing fails

[Jonas Ådahl <jadahl src gnome org>]

commit ab541e3e0fac750b7c01c441390f5259b4ace3a9
Author: Rui Matos <tiagomatos gmail com>
Date:   Tue Sep 19 19:07:34 2017 +0200

    monitor-config-migration: Fix a minor leak when parsing fails
    
    https://bugzilla.gnome.org/show_bug.cgi?id=787477

 src/backends/meta-monitor-config-migration.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/backends/meta-monitor-config-migration.c b/src/backends/meta-monitor-config-migration.c
index b820e81..6164d9f 100644
--- a/src/backends/meta-monitor-config-migration.c
+++ b/src/backends/meta-monitor-config-migration.c
@@ -652,6 +652,7 @@ load_config_file (GFile   *file,
         g_array_free (parser.output_array, TRUE);
 
       free_output_key (&parser.key);
+      g_free (parser.output_field);
       g_hash_table_destroy (parser.configs);
 
       return NULL;