contrib(UWP): (fix)bumps pthreads to avoid deadlock during upnp init

After removing the boost dependency, the Ring UWP was unable to load
accounts with upnp enabled, as a deadlock would occur within the
threadpool initialization rountine of libupnp. I think the windows store
build of pthreads was preventing win32 thread management api symbols
from being defined. Something which loading boost must have been doing.

- Bumps pthreads-win32 from 2.9.1-release to 2.10.0-rc
- Builds a win32 static lib without windows store flags and uwp libs
- Modifies the libupnp and threadutils vs project patching

Change-Id: I3f43a066d86d284c614521fdb016810148590e70