pkgsrc-dewey combining or sorting?

[David Holland <dholland-pkgtech%netbsd.org@localhost>]

Is there an off-the-shelf way to take a list of depend rules, like
these:

   inputproto>=2.0:../../x11/inputproto
   inputproto>=1.4:../../x11/inputproto
   kbproto>=1.0.2:../../x11/kbproto
   libX11>=0.99:../../x11/libX11
   libX11>=1.3:../../x11/libX11
   libX11>=1.1:../../x11/libX11
   libXext>=0.99.0:../../x11/libXext
   libXext>=1.1:../../x11/libXext

and either combine, filter, or sort so as to be able to get the real
minimum version number for each package?

pkgtools/verifypc contains some seddery for this, but it isn't general
enough and also doesn't work right in some cases.

-- 
David A. Holland
dholland%netbsd.org@localhost