MINOR: tcp-rules: Kill connections when custom actions return ACT_RET_ERR

MINOR: tcp-rules: Kill connections when custom actions return ACT_RET_ERR

Thanks to the commit "MINOR: actions: Use ACT_RET_CONT code to ignore an error
from a custom action", it is now possible to trigger an error from a custom
action in tcp-content rules. Now, when a custom action returns the ACT_RET_ERR
code, it has the same behavior than a reject rules, the connection is killed.

Be careful if this patch is backported. The other mentioned patch must be
backported first.