Add a test program for the bug described in this PR.
This is the first pkill/pgrep/prenice test (more would be good!)
This test has been confirmed to work once the bug described in the PR
has been fixed, so the test is not marked "expected to fail" even
though initially that is what should happen.
Note: the test cana also fail if the system running the tests happens
to be running processes with names that match the patterns searched for
by the test, other than the test program itself. This is expected to be
unlikely.
kre