Remove 00-test_checkexes.t, as it has lost its relevance

In the early stages of creating the new test framework,
00-test_checkexes was a temporary check to ensure we had a recipe for
every test program in test/.  By now, this test has fulfilled its
purpose, and we've learned how to make recipes properly.  It's time
for this check to go away.

Reviewed-by: Rich Salz <rsalz@openssl.org>