[PATCH 2/5] msvcr110: Add _Cancellation_beacon::_Cancellation_beacon_ctor stub.

[Piotr Caban]

Hi Torge,

Please focus on implementing _StructuredTaskCollection first. I think it 
should be quite easy to implement the class correctly after it's done. 
It's another case when incorrect implementation may cause hard to debug 
bugs.

Thanks,
Piotr