Log Message:
Don't install to $PREFIX/freetds anymore.

Discussed with maintainer and tech-pkg in November. (I don't use
this software myself, but initially looked at this to fix the manual
page installation.)

Get rid of BUILDLINK_PASSTHRU_DIRS as not needed now.

Bump PKGREVISION.

BUILDLINK_RECOMMENDED.freetds removed. And BUILDLINK_DEPENDS.freetds
set to this new version.

TODO: allow threadsafe on platforms that support it.