Make it possible to select or deselect test groups by number

Examples of possible expressions (adapt to your platform):

    make test TESTS=-99
    make test TESTS=10
    make test TESTS=-9?
    make test TESTS=-[89]0
    make test TESTS=[89]0

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2887)