Filter expected failures from JUnit output

Piglit test results are difficult to analyze with simpler JUnit
visualizers like those provided by Jenkins.  There are hundreds of
failures, but the engineer is typically interested only in NEW
failures.  Jenkins JUnit rules typically expect 100% pass rate, or
some static threshold of failures.

Specifying test names in the [expected-failures] or [expected-crashes]
sections of the config file enables JUnit reporting of just the test
failures which represent new regressions.

Test names are expected in the dotted JUnit format (eg:
"piglit.spec.ARB_fragment_program.fp-formats") and are case
insensitive.