[headsup] latest changes to bsd.perl.mk, and regressions

[Mark Linimon]

This should fix the remaining perl-related problems that people were seeing,
each related to ports that conditionally included perl.

The only remaining regressions that I can't yet explain are the following:

  */fpc-* fail to compile due some kind of flag failure.  (They work on
    my 6.2 machine here).
  lang/dylan does not seem to build reliably.
  */hs-* are refusing to install.

Someone's going to need to help me out with these.  Thanks.

mcl