So I looked at the CVS logs, and I see the following commit.

While I appreciate Todd's intent here, there *has* to be a way to do
this without making pkgsrc ungodly slow.


revision 1.275
date: 1999/05/24 23:04:52;  author: tv;  state: Exp;  lines: +38 -52
...
- Add a new target, "check-depends", which is called as part of "real-fetch".
  This validates whether the dependencies of a pkg to be built are installed,
  and if not, whether those dependencies will prospectively build (will
  not set IGNORE directly or indirectly through the various disable options).
  Recurses to "depends" with a DEPENDS_TARGET of "check-depends".

...And now, it is no longer necessary to mark dependent pkgs as unusable
when their dependencies are unusable thanks to an incorrect LICENSE,
_FOR_PLATFORM setting, and so forth.  The check-depends step will validate
everything before fetching a single file.