Fix OOM handling in fast-path

Previous fast-path malloc implementation failed to arrange proper oom
handling for operator new. I.e. operator new is supposed to call new
handler and throw exception, which was not arranged in fast-path case.

Fixed code now passes pointer for oom function to
ThreadCache::FetchFromCentralCache which will call it in oom
condition. Test is added to verify correct behavior.

I've also updated some fast-path-related comments for more accuracy.
4 files changed