[BUG] initialize msg->sol before parsing first line

Before calling http_parse_{sts,req}line(), it is necessary
to make msg->sol point to the beginning of the line. This
was not done, resulting in the proxy sometimes crashing when
URI rewriting or result rewriting was used.
diff --git a/src/proto_http.c b/src/proto_http.c
index 236e774..38b2db0 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -3998,6 +3998,7 @@
 			txn->req.eoh += delta;
 			cur_end += delta;
 
+			txn->req.sol = req->data + txn->req.som;
 			cur_end = (char *)http_parse_reqline(&txn->req, req->data,
 							     HTTP_MSG_RQMETH,
 							     cur_ptr, cur_end + 1,
@@ -4563,6 +4564,7 @@
 			txn->rsp.eoh += delta;
 			cur_end += delta;
 
+			txn->rsp.sol = rtr->data + txn->rsp.som;
 			cur_end = (char *)http_parse_stsline(&txn->rsp, rtr->data,
 							     HTTP_MSG_RPVER,
 							     cur_ptr, cur_end + 1,