mingw-w64 currently is lacking the headers for this feature.
Make the include lowercase at the same time. We consistently use lowercase for windows header includes, as windows itself is case insensitive, the SDK headers (in general, not necessarily considering this particular header) aren't consistent among themselves about what the proper canonical capitalization for headers are, and MinGW uses all lowercase names for the headers (as it is often used on case sensitive filesystems).
In case mingw-w64 later gets this header, we can revert this (but keep the include lowercased).