Bug 799092 - GnuCash 5.4 leaves background process running on exit

Clear the schema_hash at app shutdown via gnc_prefs_remove_registered
and make that function available to the Python bindings so that
python programs can do so too.

bindings/app-utils.i

@@ -57,6 +57,7 @@ PyObject* SWIG_init (void);
 %import "base-typemaps.i"
 
 void gnc_prefs_init();
+void gnc_prefs_remove_registered();
 
 QofBook * gnc_get_current_book (void);
 QofSession * gnc_get_current_session (void);

libgnucash/app-utils/gnc-gsettings.cpp

@@ -522,9 +522,7 @@ void gnc_gsettings_load_backend (void)
     if (g_strcmp0 (g_getenv ("GNC_UNINSTALLED"), "1") == 0)
         return;
 
-    if (prefsbackend)
-        g_free (prefsbackend);
-
+    g_free (prefsbackend);
     prefsbackend = g_new0 (PrefsBackend, 1);
 
     prefsbackend->register_cb = gnc_gsettings_register_cb;
@@ -560,6 +558,12 @@ void gnc_gsettings_load_backend (void)
     LEAVE("Prefsbackend bind = %p", prefsbackend->bind);
 }
 
+void
+gnc_gsettings_shutdown (void)
+{
+    schema_hash.clear();
+    g_free (prefsbackend);
+}
 
 
 static GVariant *

libgnucash/app-utils/gnc-gsettings.h

@@ -570,6 +570,10 @@ void gnc_gsettings_reset_schema (const gchar *schema);
  */
 void gnc_gsettings_load_backend (void);
 
+/** Free the GSettings resources.
+ */
+void gnc_gsettings_shutdown (void);
+
 /** Check whether we need to adjust the user settings
  * to a newer version.
  *

libgnucash/app-utils/gnc-prefs-utils.c

@@ -139,4 +139,5 @@ gnc_prefs_remove_registered (void)
                            file_retain_type_changed_cb, NULL);
     gnc_prefs_remove_cb_by_func (GNC_PREFS_GROUP_GENERAL, GNC_PREF_FILE_COMPRESSION,
                            file_compression_changed_cb, NULL);
+    gnc_gsettings_shutdown ();
 }