Log Message:
geography/osm2pgsql: Convert to cmake/build.mk

  - drop ad-hoc build dir creation and use

Minor other changes to get this closer to building:

  - drop WRKSRC setting because it just restates the default
  - add python to tools, as documented by upstream
  - add python/application.mk to work around upstream CMakefile
    finding and objecting to 2.7.

(Didn't build before this commit, and still doesn't, but this is
progress.  Likely an update is needed, as this version seems to have
aged out of what our current cmake supports.)