bugfix: strip comments in drill/dig output when checking txt in dns.

The dns query is often being reprinted as a comment as part of the drill/dig output
this caused multiple hits for the grep, making the comparison invalid.
Make sure we strip out comments before we look for the challenge text in the txt record.

getssl

@@ -1203,6 +1203,7 @@ if [[ $VALIDATE_VIA_DNS == "true" ]]; then
           elif [[ "$DNS_CHECK_FUNC" == "drill" ]] || [[ "$DNS_CHECK_FUNC" == "dig" ]]; then
             debug "$DNS_CHECK_FUNC" TXT "_acme-challenge.${lower_d}" "@${ns}"
             check_result=$($DNS_CHECK_FUNC TXT "_acme-challenge.${lower_d}" "@${ns}" \
+                           | grep -i "^_acme-challenge.${lower_d}" \
                            | grep 'IN\WTXT'|awk -F'"' '{ print $2}')
           elif [[ "$DNS_CHECK_FUNC" == "host" ]]; then
             check_result=$($DNS_CHECK_FUNC -t TXT "_acme-challenge.${lower_d}" "${ns}" \