MINOR: mux-h1: Don't emit C-L and T-E headers for 204 and 1xx responses

204 and 1xx responses must not have any payload. Now, the H1 mux takes care
of that in last resort. But they also must not have any C-L or T-E
headers. Thus, if found on the sending path, these headers are ignored.
diff --git a/src/mux_h1.c b/src/mux_h1.c
index 7b99f1a..266a2e7 100644
--- a/src/mux_h1.c
+++ b/src/mux_h1.c
@@ -1828,9 +1828,14 @@
 				if (*(n.ptr) == ':')
 					goto skip_hdr;
 
-				if (isteq(n, ist("transfer-encoding")))
+				if (isteq(n, ist("transfer-encoding"))) {
+					if ((h1m->flags & H1_MF_RESP) && (h1s->status < 200 || h1s->status == 204))
+						goto skip_hdr;
 					h1_parse_xfer_enc_header(h1m, v);
+				}
 				else if (isteq(n, ist("content-length"))) {
+					if ((h1m->flags & H1_MF_RESP) && (h1s->status < 200 || h1s->status == 204))
+						goto skip_hdr;
 					/* Only skip C-L header with invalid value. */
 					if (h1_parse_cont_len_header(h1m, &v) < 0)
 						goto skip_hdr;