Fix Case of ShLwApi
Fix Case of ShLwApi

The Shell Lightweight API is spelled `ShLwApi` (however, the header is
spelled `Shlwapi`). This allows llbuild to compile targeting Windows on
case sensitive platforms.

apple/swift-llbuild,apple/swift-llbuild,apple/swift-llbuild,apple/swift-llbuild,apple/swift-llbuild,apple/swift-llbuild,apple/swift-llbuild