MINOR: http-rules: Add a rule result to report internal error

Now, when HTTP rules are evaluated, HTTP_RULE_RES_ERROR must be returned when an
internal error is catched. It is a way to make the difference between a bad
request or a bad response and an error during its processing.
diff --git a/include/types/http_ana.h b/include/types/http_ana.h
index 4956d68..dd55eb8 100644
--- a/include/types/http_ana.h
+++ b/include/types/http_ana.h
@@ -125,6 +125,7 @@
 	HTTP_RULE_RES_ABRT,      /* abort request, msg already sent (eg: auth) */
 	HTTP_RULE_RES_DONE,      /* processing done, stop processing (eg: redirect) */
 	HTTP_RULE_RES_BADREQ,    /* bad request */
+	HTTP_RULE_RES_ERROR,     /* Internal error */
 };
 
 /* Legacy version of the HTTP/1 message state, used by the channels, should