[libFuzzer] Stop fuzzing if no new corpus were found within a specified period (#176177) This patch adds a new command-line option `-stale_corpus_timeout=N` which allows you to specify that the fuzzer should exit if it hasn't found a new corpus within a certain amount of time. It also adds to stats how many seconds a new path has not been found. An analog of `AFL_EXIT_ON_TIME`. GitOrigin-RevId: af2d76922b54fc347faac9727b0748387fea043f