The H1_MF_CLEN flag is needed to figure whether a content-length header is
present or not when producing a request, so let's check it on output just
like we already check the transfer-encoding header.
if (isteqi(n, ist("transfer-encoding")))
h1_parse_xfer_enc_header(h1m, v);
+ else if (isteqi(n, ist("content-length"))) {
+ if (h1_parse_cont_len_header(h1m, &v) <= 0)
+ goto skip_hdr;
+ }
else if (isteqi(n, ist("connection"))) {
h1_parse_connection_header(h1m, v);
h1_process_conn_mode(h1s, h1m, NULL, &v);