tools/pkgconf: update to 2.0.1

tools/pkgconf: update to 2.0.1

Changes from 2.0.0 to 2.0.1:
----------------------------

* The behavior of --modversion was largely reverted back to the traditional
  pkg-config behavior, but still operates on a solved dependency graph.

  The order of --modversion output is based on the dependency resolution
  queue which is passed to the solver, which itself generally maps to the
  order of the constrants provided on the command line.

* A new flag, --verbose, has been added.  When used with `--modversion`, it
  is possible to disambiguate which version belongs to which module:

    % pkgconf --modversion --verbose foo bar
    foo: 1.2.3
    bar: 1.3

Changes from 1.9.5 to 2.0.0:
----------------------------

* When flattening the dependency graph, retain the latest seen edges
  rather than the earliest.

* Fix a long-standing bug where the dependency resolution queue was
  evaluated in reverse.  This bug masked the aforementioned dependency
  flattening bug in many cases.

* Fix handling of --with-path, which was appending paths to the search
  list rather than prepending them as intended.

* Error when --modversion is requested with more than one package, as
  the output is ambiguous.

Signed-off-by: Rosen Penev <rosenp@gmail.com>