cdr_adaptive_odbc: Also apply a filter when the CDR value is empty.

Extra CDR records are written if a filtered CDR value is empty because the
filter is not checked.

(closes issue ASTERISK-22272)
Reported by: Jordi Llull Chavarria


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/1.8@401577 f38db490-d61c-443f-a65b-d21fe96a405b