* In the fatal_signal test, wait for the daemon to receive FUSE_INTERRUPT
before exiting.
* Explicitly disable restarting syscalls after SIGUSR2. This fixes
intermittency in the priority test. I don't know why, but sometimes that
test's mkdir would be restarted, and sometimes it would return EINTR.
ERESTART should be the default.
* Remove a useless copy/pasted sleep in the priority test.