These tests come from several sources, notably a test-suite started by
Henry Spencer, and the "Khadafy" test suite by Scott Anderson.

Originally these tests were put together to test the correctness of
the results returned by Rx, but here, they are being used as a timing
test.

The strings being compared to regexps by these tests are all very short.
As a result, this is mostly a test of the performance of regcomp, not 
of regexec.

