patch: handle submitted complilation error

[neenjaw]

Presently a compilation error was classified as a test failure, however this causes the website to show all of the dependent test cases which appear to be passing (despite actually not being run), because the j-unit output doesn't have a success child element to indicate success, only the absense of a skipped/failure element indicates success.

[neenjaw]

Following the CI run here: Will need to more closely look at how to consider errors in test cases as distinct from errors in the test file.

[mk-mxp]

Maybe you can run php -l $solution_file to separately lint the students file for errors and not run PHPUnit at all when that fails?