Prep Flatpak manifest for Flathub stable submission

flatpak/Load-plugins-from-Flatpak-extensions.patch

@@ -1,25 +1,17 @@
-From 918503d57c6740d20be68a6717158673a2a8b25f Mon Sep 17 00:00:00 2001
-From: Patrick Griffis <tingping@tingping.se>
-Date: Sat, 17 Mar 2018 05:57:49 -0400
-Subject: [PATCH] Support loading Flatpak extensions
-
----
- src/common/plugin.c | 2 ++
- 1 file changed, 2 insertions(+)
-
-diff --git a/src/common/plugin.c b/src/common/plugin.c
-index 3ad3c558..6addf962 100644
 --- a/src/common/plugin.c
 +++ b/src/common/plugin.c
-@@ -450,6 +450,8 @@ plugin_auto_load (session *sess)
- 	lib_dir = plugin_get_libdir ();
- 	sub_dir = g_build_filename (get_xdir (), "addons", NULL);
- 
-+	for_files ("/app/extensions/lib/zoitechat/plugins", "*.so", plugin_auto_load_cb);
+@@ -470,7 +470,14 @@
+ 	if (libdir && *libdir)
+ 		return libdir;
+ 	else
++	{
++		if (g_file_test ("/app/extensions/lib/zoitechat/plugins", G_FILE_TEST_IS_DIR))
++		{
++			return "/app/extensions/lib/zoitechat/plugins";
++		}
 +
- #ifdef WIN32
- 	/* a long list of bundled plugins that should be loaded automatically,
- 	 * user plugins should go to <config>, leave Program Files alone! */
--- 
-2.14.3
-
+ 		return ZOITECHATLIBDIR;
++	}
+ }
+ 
+ void