[MINOR] http redirect: don't explicitly state keep-alive on 1.1

Do not set the "connection: keep-alive" header when the request is in
HTTP 1.1, it's implicit.
diff --git a/src/proto_http.c b/src/proto_http.c
index f2f312e..92c5869 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -2867,8 +2867,12 @@
 			    ((txn->flags & TX_CON_WANT_MSK) == TX_CON_WANT_SCL ||
 			     (txn->flags & TX_CON_WANT_MSK) == TX_CON_WANT_KAL)) {
 				/* keep-alive possible */
-				memcpy(rdr.str + rdr.len, "\r\nConnection: keep-alive\r\n\r\n", 28);
-				rdr.len += 28;
+				if (!(txn->flags & TX_REQ_VER_11)) {
+					memcpy(rdr.str + rdr.len, "\r\nConnection: keep-alive", 24);
+					rdr.len += 24;
+				}
+				memcpy(rdr.str + rdr.len, "\r\n\r\n", 4);
+				rdr.len += 4;
 				buffer_write(req->prod->ob, rdr.str, rdr.len);
 				/* "eat" the request */
 				buffer_ignore(req, msg->sov - msg->som);