This test was previously tweaked in
321f696920 to match the output of
of MS STL (except that the MS STL fails on the testcase with an
empty path).
libc++ doesn't produce paths with all normalized separators (and the
spec doesn't mandate it to either).
Tweak the test reference to match exactly what libc++ produces. If
testing with a non-libc++ library, do a relaxed comparison that allows
the separators to differ.
Differential Revision: https://reviews.llvm.org/D98215