Improve PSAPI.dll detection (#1391)

Improve PSAPI.dll detection (#1391)

Detect Windows PSAPI library like any other library dependency. Allowing
build --with(out) options to disable or to set paths.

Detect the psapi.h properly and set HAVE_* macro for proper include
wrapping.

Wrap PSAPI logic in check for PSAPI_VERSION which is defined whenever
the API support is actually available.