We had all tests run with test/test-runs/ as working directory, and
tests cleaned up after themselves... which is well and good, until
you want to have a look at what went wrong when a complex test fails,
and you have to recreate everything it does manually.
To remedy this, we have OpenSSL::Test create the result directory
dynamically (and cleaning it up first if it's already there) and let
the test recipe have that as working directory.
Test recipes are now encouraged to name their diverse output files
uniquely, and not to clean them up, to allow a developer to have a
look at the files that were produced.
With continuous integration that allows this, the result directories
could also be archived and be left as a build artifact.
Reviewed-by: Paul Dale <email@example.com>
(Merged from https://github.com/openssl/openssl/pull/11080)