Avoid creating any temporary files in the current workdir.
Additional/changing files in the bin/tests/system directory are
problematic for pytest/xdist collection phase, which assumes the list of
files doesn't change between the collection phase of the main pytest
thread and the subsequent collection phase of the xdist worker threads.
Since the testcrypto.sh is also called during pytest initialization
through conf.sh.common (to detect feature support), this could
occasionally cause a race condition when the list of files would be
different for the main pytest thread and the xdist worker.
Multiple algorithm sets can be defined in this script. These can be
selected via the ALGORITHM_SET environment variable. For compatibility
reasons, "stable" set contains the currently used algorithms, since our
system tests need some changes before being compatible with randomly
selected algorithms.
The script operation is similar to the get_ports.py - environment
variables are created and then printed out as `export NAME=VALUE`
commands, to be interpreted by shell. Once we support pytest runner for
system tests, this should be a fixture instead.
