Switch "windows" to "system-windows" in some XFAILs

The test failure mode appears to be due to the host machine rather than the
target. The PS4 buildbots are windows-hosted targeting x86_64-scei-ps4,
and are currently reporting these as unexpected failures:

  http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-scei-ps4-windows10pro-fast/builds/28114

llvm-svn: 371726