Remove g_type_init() calls

Very many testcases, some GLib tools (resource compiler, etc) and
GApplication were calling g_type_init().

Remove those uses, as they are no longer required.

https://bugzilla.gnome.org/show_bug.cgi?id=686161

gio/tests/gdbus-example-watch-proxy.c

@@ -153,8 +153,6 @@ main (int argc, char *argv[])
   GDBusProxyFlags flags;
   GDBusProxy *proxy;
 
-  g_type_init ();
-
   loop = NULL;
   proxy = NULL;