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

tests/timeloop-closure.c

@@ -187,8 +187,6 @@ main (int argc, char **argv)
   struct rusage old_usage;
   struct rusage new_usage;
 
-  g_type_init ();
-  
   if (argc > 1)
     n_children = atoi(argv[1]);