This allows pyenchant to be installable on macOS again, which, in turn, will allow pylint
to also be installable.
* Switches dependencies to enchant-2 (enchant-1 is not building on macOS). The existing $src (2.0.0) already has compatibility with enchant-2.
* Improves patch hack by hijacking the $PYENCHANT_LIBRARY_PATH envvar lookup
to explicitly specify the correct library path.