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/gobject/override.c

@@ -400,7 +400,6 @@ main (int argc, char **argv)
   g_log_set_always_fatal (g_log_set_always_fatal (G_LOG_FATAL_MASK) |
 			  G_LOG_LEVEL_WARNING |
 			  G_LOG_LEVEL_CRITICAL);
-  g_type_init();
 
   test (TEST_TYPE_A, "foo", "TestA::foo,TestI::foo", NULL);
   test (TEST_TYPE_A, "bar", "TestA::bar", NULL);