BUG/MINOR: http-ana: Increment failed_resp counters on invalid response

In http_process_res_common() analyzer, when a invalid response is reported, the
failed_resp counters must be incremented.

No need to backport this patch, except if the commit b8a5371a ("MEDIUM:
http-ana: Properly handle internal processing errors") is backported too.
diff --git a/src/http_ana.c b/src/http_ana.c
index 2548a9a..7ff474e 100644
--- a/src/http_ana.c
+++ b/src/http_ana.c
@@ -2159,6 +2159,11 @@
 
  return_bad_res:
 	txn->status = 502;
+	_HA_ATOMIC_ADD(&s->be->be_counters.failed_resp, 1);
+	if (objt_server(s->target)) {
+		_HA_ATOMIC_ADD(&__objt_server(s->target)->counters.failed_resp, 1);
+		health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_RSP);
+	}
 	/* fall through */
 
  return_prx_err: