[gobject] Remove hb_language_t workarounds for g-i shortcomings

Using latest gobject-introspection, I don't seem to be having this
problem anymore:

  https://bugzilla.gnome.org/show_bug.cgi?id=707656

Removing that kludge makes language_t behave more like the way I expect it
in Python.

Also fixes:
https://github.com/behdad/harfbuzz/issues/91
2 files changed