mscoree: Add CorIsLatestSvc function stub.

[Andrey Gusev]

>From poking at it with python ctypes, I believe this function takes 2
>pointer arguments and returns an HRESULT.

>Have you found a real app that calls this? As far as I know, it's only
>called by native .NET components that shouldn't be used with builtin
>mscoree.

At least two apps calls this function after .NET 4.5.1 (offline) have
been installed.