audio/py-pyogg: adjust dependencies' type, prevent PATH poisoning

Contrary to Windows, we use colons to separate directories in the
PATH environment variable; however, this code is still useless as
it does not affect ctypes.util.find_library() search logic.

Since libraries are opened during tun-time, LIB_DEPENDS should be
actually specified as RUN_DEPENDS here (this would also hopefully
prevent needless port revision bumps in the future).