Make the last to clangd unit tests pass on Windows.
Make the last to clangd unit tests pass on Windows.

(Some lit tests still fail.)

See FIXME in diff for details.

Part of PR43592.

git-svn-id: a34e9779ed74578ad5922b3306b3d80a0c825546@374727 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra