PYTHON_VERSIONS_INCOMPATIBLE=27 cleanup

[Thomas Klausner <wiz%NetBSD.org@localhost>]

Hi!

Since packages now have to be marked (with PYTHON_27_ACCEPTED) if they
support Python 2,

PYTHON_VERSIONS_INCOMPATIBLE=27

does not make any sense any longer (it's the default).

I suggest we remove these lines from pkgsrc.

Any comments?
 Thomas