ports/127661: [PATCH]textproc/libxml2: update to 2.7.1, which includes security fixes

[bf]

Jeremy:

Don't forget the needed alteration to the pkg-plist for py-libxml2 that was
in one of my earlier messages: I didn't see it in the MC repo.  

So now you know: if you want to update a port, but don't have the time or
the desire to do it yourself, just mark it as vulnerable with portaudit.  ;)

Regards,
          b.