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-peer.c

@@ -177,8 +177,6 @@ main (int argc, char *argv[])
 
   ret = 1;
 
-  g_type_init ();
-
   opt_address = NULL;
   opt_server = FALSE;
   opt_allow_anonymous = FALSE;