Report crashes during serach compilation/benchmark (#384)
Report crashes during serach compilation/benchmark (#384)

This fixes a deadlock during search when a process crashes. In that
case, search is now aborted.
iree-org/iree-llvm-sandbox,iree-org/iree-llvm-sandbox,iree-org/iree-llvm-sandbox,iree-org/iree-llvm-sandbox