threadname: add support for SetThreadDescription
threadname: add support for SetThreadDescription

Summary:
Windows 10, starting with 1607, has a public API for setting thread
names. Profilers can use this information even when the process does
not have a debugger attached.

Try calling SetThreadDescription before falling back to the MSVC
debugger interrupt protocol.

Reviewed By: yfeldblum

Differential Revision: D36338834

fbshipit-source-id: 799fcda711d6c6d2b46bd6fd24beb6981b705ccc

facebook/folly,facebook/folly,facebook/folly,facebook/folly,facebook/folly