pkgconf: upgrade 2.1.1 -> 2.2.0

pkgconf: upgrade 2.1.1 -> 2.2.0

Changelog:
===========
* libpkgconf SOVERSION is now 5.
* Significant solver rework to flatten both requires and requires.private
  dependencies in a single pass.  Improves performance slightly and ensures
  proper dependency order.
* Improve '--digraph' output to reflect more of the solver's state in the
  rendered dependency graph.
* Do not reference the graph root by name when presenting error messages about
  directly requested dependency nodes.

Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>