FIBER_TASKING_LIB: Make int64 portable
FIBER_TASKING_LIB: Make int64 portable

underscorediscovery/FiberTaskingLib,underscorediscovery/FiberTaskingLib,Samana/FiberTaskingLib,jklarowicz/FiberTaskingLib,jklarowicz/FiberTaskingLib,Samana/FiberTaskingLib,jklarowicz/FiberTaskingLib