BUG/MINOR: mux-h1: Adjust header case when chunked encoding is add to a message

When an outgoing h1 message is formatted, if it is considered as chunked but the
corresponding header is missing, we add it. And as all other h1 headers, if
configured so, the case of this header must be adjusted.

No backport needed.
diff --git a/src/mux_h1.c b/src/mux_h1.c
index 230903b..60461a8 100644
--- a/src/mux_h1.c
+++ b/src/mux_h1.c
@@ -1685,7 +1685,11 @@
 				     (h1m->flags & (H1_MF_VER_11|H1_MF_RESP|H1_MF_CLEN|H1_MF_CHNK|H1_MF_XFER_LEN)) ==
 				     (H1_MF_VER_11|H1_MF_RESP|H1_MF_XFER_LEN))) {
 					/* chunking needed but header not seen */
-					if (!chunk_memcat(&tmp, "transfer-encoding: chunked\r\n", 28))
+					n = ist("transfer-encoding");
+					v = ist("chunked");
+					if (h1c->px->options2 & (PR_O2_H1_ADJ_BUGCLI|PR_O2_H1_ADJ_BUGSRV))
+						h1_adjust_case_outgoing_hdr(h1s, h1m, &n);
+					if (!htx_hdr_to_h1(n, v, &tmp))
 						goto copy;
 					TRACE_STATE("add \"Transfer-Encoding: chunked\"", H1_EV_TX_DATA|H1_EV_TX_HDRS, h1c->conn, h1s);
 					h1m->flags |= H1_MF_CHNK;