[libcxx] Fixing the test-suite breakage on the 3.6/3.6.1 branch.

(Re-sending this email to cfe-dev)

I just discovered that a bad merge broke libc++'s test-suite
configuration in 3.6.0 (r226859). The only file that was merged improperly is
`libcxx/test/libcxx/test/config.py`. This breakage prevents the
test-suite from being run.

If possible, I would like to fix the test-suite in 3.6.1. Otherwise
3.6.2 is fine. The patch is linked below. The patch should be very
safe to apply since it doesn't affect the build or libc++ itself.


Offending commit:

Fix: libc++ 3.6 test suite fix ยท GitHub