Currently, scan-dump variants treat a missing dump file as a failure and
append ": dump file does not exist" to the test message that would be
used with pass or fail.  This patch treats it as unresolved instead,
using the same test message as for pass/fail and reporting the reason
in the log file.

Tested with dummy tests that use all of these procs for either pass,
fail, or unresolved.  OK for trunk, and later for 4.6?

Janis