pdbtool test: return failure in case an example pattern didn't match

This patch fixes pdbtool test so it returns non-zero as an exit code
in case the supplied example message for a pattern didn't match.

Reported-By: Evan Rempel <erempel@uvic.ca>
Signed-off-by: Balint Kovacs <blint@balabit.hu>
Signed-off-by: Balazs Scheidler <bazsi@balabit.hu>