Fix windows SEH hook when crashing in an std::thread

Follows rP22649 and other 'pthread->std::thread' diffs.

Windows uses Structured Exception Handling to allow reporting errors (both C++ and hardware) nicely. This works by wrapping the code in a try catch block.
The pthread wrapper did this automatically, but we now need to do it explicitly for std::thread.

Tested by: Stan

Differential Revision: https://code.wildfiregames.com/D3261