libgxim: move from meta-ruby back to meta-oe

* it was moved to meta-ruby (totherer with imsettings which depends on libgxim)
  because of ruby-native dependency, now when ruby was moved from meta-ruby to
  oe-core we can move libgxim back to meta-oe (which also allows imsettings
  in meta-xfce to depend only on meta-oe as well)

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>