BUG/MEDIUM: mux-h2: Don't forget to set the CS_FL_EOS flag with htx.

When running with HTX, if we got an empty answer, don't forget to set
CS_FL_EOS, or the stream will never be destroyed.
diff --git a/src/mux_h2.c b/src/mux_h2.c
index c83230a..f16da22 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -4488,8 +4488,11 @@
 	if (h2c->proxy->options2 & PR_O2_USE_HTX) {
 		/* in HTX mode we ignore the count argument */
 		h2s_htx = htx_from_buf(&h2s->rxbuf);
-		if (htx_is_empty(h2s_htx))
+		if (htx_is_empty(h2s_htx)) {
+			if (cs->flags & CS_FL_REOS)
+				cs->flags |= CS_FL_EOS;
 			goto end;
+		}
 
 		buf_htx = htx_from_buf(buf);
 		count = htx_free_space(buf_htx);