Revert "[DirectoryWatcher] Replace buffer length macro with constexpr"
Revert "[DirectoryWatcher] Replace buffer length macro with constexpr"

This reverts commit fea201fb2fe647a5642c3d8534c1b3a8b1cb8572.

apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang