Provided Basic Support for -l N option on windows platform.

I have implemented basic support for **-l N** on windows platform.

Tested with platform==msvc and platform==mingw.

Values returned from OS are filtered with basic filter, to minimize load variation caused by short time between consecutive calls.

I have tested it on 2 core machine with HT and 4 core one, and CPU load in Task Manager matches one provided in -l option.

Any suggestion and improvements are more than welcome.


Should this be done unconditionally? Why 0.9 and 0.1? If the system is at 0 load, and then gets to 100%, it'll take 10 calls to this function until load actually reaches 1. This function is called once per started job – if jobs run long, that can be a long time where load increase isn't noticed. If you want to smooth, maybe this should take ticks_since_last_time into account? Or maybe just don't smooth at all at first?