make devel/boehm-gc build on Bitrig. boehm-gc doesn't use autoconf
Let python3 ports use setuptools.

The distribute fork has been merged back into setuptools and is now
discontinued.

ok bket@
Remove py-distribute.

The project is discontinued. All efforts have been merged back to
setuptools.

ok bket@
Update devel/py-setuptools to 5.4.2.

ok bket@
Add quirk for py3-distribute -> py3-setuptools.

ok bket@
Bump REVISION for all python3 ports.

ok bket@