MINOR: mux-quic: adjust return value of decode_qcs

Use 0 for success of decode_qcs operation else non-zero. This is to
follow the same model which is in use in most of the function in MUX/H3
code.
diff --git a/src/h3.c b/src/h3.c
index 0fd22fe..1b7b302 100644
--- a/src/h3.c
+++ b/src/h3.c
@@ -261,7 +261,8 @@
 
 /* Decode <qcs> remotely initiated bidi-stream. <fin> must be set to indicate
  * that we received the last data of the stream.
- * Returns <0 on error else 0.
+ *
+ * Returns 0 on success else non-zero.
  */
 static int h3_decode_qcs(struct qcs *qcs, int fin, void *ctx)
 {
diff --git a/src/hq_interop.c b/src/hq_interop.c
index a47f5d1..651afb5 100644
--- a/src/hq_interop.c
+++ b/src/hq_interop.c
@@ -64,7 +64,7 @@
 
 	sl = htx_add_stline(htx, HTX_BLK_REQ_SL, 0, ist("GET"), path, ist("HTTP/1.0"));
 	if (!sl)
-		return -1;
+		return 1;
 
 	sl->flags |= HTX_SL_F_BODYLESS;
 	sl->info.req.meth = find_http_meth("GET", 3);
@@ -74,7 +74,7 @@
 
 	cs = qc_attach_cs(qcs, &htx_buf);
 	if (!cs)
-		return -1;
+		return 1;
 
 	qcs_consume(qcs, ncb_data(rxbuf, 0));
 	b_free(&htx_buf);
diff --git a/src/mux_quic.c b/src/mux_quic.c
index 6754d3b..d744f91 100644
--- a/src/mux_quic.c
+++ b/src/mux_quic.c
@@ -433,7 +433,7 @@
 {
 	TRACE_ENTER(QMUX_EV_QCS_RECV, qcc->conn, qcs);
 
-	if (qcc->app_ops->decode_qcs(qcs, qcs->flags & QC_SF_FIN_RECV, qcc->ctx) < 0) {
+	if (qcc->app_ops->decode_qcs(qcs, qcs->flags & QC_SF_FIN_RECV, qcc->ctx)) {
 		TRACE_DEVEL("leaving on decoding error", QMUX_EV_QCS_RECV, qcc->conn, qcs);
 		return 1;
 	}