[libc++] Fix XFAILs on macOS when exceptions are disabled

Some tests are marked as failing on platforms where the dylib does not
provide the required exception classes. However, when testing with
exceptions disabled, those tests shouldn't be marked as failing.

llvm-svn: 353210
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: f5f2f77755072888e955d05bc0ff568b18260ca0
45 files changed