Rollup merge of #44374 - jsheard:threadname, r=alexcrichton

Implement named threads on Windows (v2)

https://msdn.microsoft.com/en-us/library/windows/desktop/mt774976(v=vs.85).aspx

Windows 10 version 1607 finally added a sensible API for naming threads, so we can now implement named threads without having to use MSVC compiler extensions like before. VS2017s debugger and the WPA profiler already use this API where available, but other tools may need some time to catch up.

![thread](https://user-images.githubusercontent.com/3153547/30133438-c92a3cda-934b-11e7-9668-915d53e8d860.png)