test: detect test failures if atexit handler calls _exit(!0) (sanitizers) tinytest uses another way of detecting test failures, it uses pipe between child and parent, and if the test function in child returns OK it writes OK flag into pipe, and reads it in parent. However sanitizers uses atexit handlers to detect leaks, and this will not detect failures in case of exit() will be called from the atexit handlers, fix this by checking status after waitpid().