Some progress for the Pidgin++ package.

* The configure script is not suitable for building Pidgin on Windows, we need
  to use the static makefiles instead, and configure the build to seek for the
  dependencies in MSYS2 itself, not in the development root described by
  https://developer.pidgin.im/wiki/BuildingWinPidgin.

* The package is not split into the pidgin++, libpurple and finch packages
  anymore, this can be done later.

* The latest Bazaar revision is used instead of a tarball.

* Source code has been refactored.

Currently the build fails at SASL stuff or something. However, the archetype for
the PKGBUILD is ready, it's now just a matter of fixing these specific issues.