Make sure we fall back to /etc/passwd if shadow is not available.

Failing is not appropriate if the file doesn't exist.
Add repeated tests for running in HPUX trusted mode.

Since HPUX can run with both /etc/shadow turned off (non trusted mode)
and on (trusted mode), we should test both. We do this by symlinking
an extra test to the original test, since the test itself is no
different. In between we enable/disable trusted mode.
Fix graceful process termination on HPUX.

The termination code requires platform code to query for process state
and start time.
Add helpful message to fix process matching on HP-UX.

We can't fix it in the code, since it is a platform attribute, and not
an argument you can pass to ps.