MINOR: quic: Fix potential null pointer dereference

Fix compilation warnings about non initialized pointers.

This partially address #1445 github issue.
diff --git a/src/xprt_quic.c b/src/xprt_quic.c
index 09722c0..0fdc7aa 100644
--- a/src/xprt_quic.c
+++ b/src/xprt_quic.c
@@ -3309,6 +3309,7 @@
 	struct quic_enc_level *qel;
 
 	qc = NULL;
+	qel = NULL;
 	TRACE_ENTER(QUIC_EV_CONN_SPKT);
 	if (end <= *buf)
 		goto err;
@@ -3461,6 +3462,7 @@
 
 	qc = NULL;
 	conn_ctx = NULL;
+	qel = NULL;
 	TRACE_ENTER(QUIC_EV_CONN_LPKT, NULL, pkt);
 	if (end <= *buf)
 		goto err;