* tests/utils.scm (temp-file): New variable.
("fcntl-flock"): Rewrite to actually test whether the child process
waits for the lock to be released. The previous test was wrong
because (1) it expected F_SETLK semantics, not F_SETLKW, and (2) it
got EBADF because of a mismatch between the open mode and the lock
style.