Unmatched messages should contain source_hostname_key or
source_address_key if configured as this information is provided by the
underlying udp oder tcp server and is available even if the message
could not be parsed.

This commit adds testcases for these options in combination with
unmatched lines.

Signed-off-by: Anselm Eberhardt <aeberhardt@dg-i.net>

Include source_address_key or source_hostname_key on unmatched lines
when configured.

This fixes the test cases added in
e3b959b.

Signed-off-by: Anselm Eberhardt <aeberhardt@dg-i.net>