Peter Hutterer authored Nov 27, 2019 and Benjamin Tissoires committed Nov 28, 2019

libcheck has the ability to write out XML files for test results, but
converting those into junit isn't ideal, for a number of reasons:
- junit xml is different to libcheck's xml, so not all data is available or
  useful. Especially with our litest wrappers around it.
- litest forking off tests means we have to wrap around everything anyway to
  avoid multiple forks writing to the same test file.

This is the minimal implementation since it's only user is likely the CI which
we control fairly tightly. So there are a few corners we can skip:
- no filename validation is performed by litest
- we write out a lot of junit xml files (one per litest fork). Rather than
  collating those we just rely on the CI to find the files.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>