as it's only used internally by bsd.prefs.mk.
* Make _PKGSRCDIR a public variable by renaming it to PKGSRCDIR.
Also, generate its value from ${_PKGSRC_TOPDIR} so it's less fragile
than the old method of stripping off the last two components of
${.CURDIR}. PKGSRCDIR may now be used after bsd.prefs.mk is defined.
* Change all references to _PKGSRCDIR to PKGSRCDIR.
Tests are found in pkgsrc/regress, tests are run by executing pkg_regress.
Based on an idea discussed at pkgsrcCon 2004. Thanks to dillo@ for review
and refinements, and to jlam@ for review.