make handling of self signed certs more robust

openssl sometimes will print the filename, then the error, and finish
with OK, matching the colon and space prevents from considering such
certs to be valid

cipherscan

@@ -221,7 +221,7 @@ test_cipher_on_target() {
             local saved="False"
             if ${OPENSSLBIN} verify "${trust_source[@]}" \
                 -untrusted <(echo "$tmp") <(echo "$cert") 2>/dev/null | \
-                grep 'OK$' >/dev/null; then
+                grep ': OK$' >/dev/null; then
 
                 # if the certificate is an intermediate CA it may be useful
                 # for connecting to servers that are misconfigured so save it