Log Message:
devel/gps: Upgrade GNAT Programming Studio to version 5.2.1

This is a significant upgrade over version 5.0.1 which is currently in
pkgsrc, representing approximately two years of work.  The latest online
documentation can be browsed here:

   http://docs.adacore.com/gps-docs/users_guide/_build/html/

Changes to the package itself include:
* python now works and is a default option
* readline support is now an option and is default
* Multiple job support enable
* Documentation now generated by sphinx

Also the problem described in PR#47824 no longer occurs, so this PR will
be closed.