Bugfix: testsuite in VASP.6.1.0 to 6.1.2 on MacOS and BSD

The vasp.6.1.0, vasp.6.1.1 and vasp.6.1.2 releases have a potentially serious issue that can lead to loss of user data unrelated to vasp in the home directory! This issue has yet been only observed on MacOS and BSD systems, but might affect other OS as well. Avoid to use

 make test
 make test_all
 make cleantest

or the use of any script called

 cleanall

on MacOS or BSD systems (and potentially other OS) until we release a fix.

This script is used to clean the files produced by VASP after running the test suite. The readlink and dirname commands take different arguments on Linux and BSD systems including macOS. On BSD systems this results in the $dir variable becoming empty, cd to the home folder and removing ALL files recursively that do not match the pre-defined patterns.