BUG/MINOR: quic: memleak on wrong datagram receipt

There was a missing pool_free() call for such datagrams. As far as I see
there is no leak on valid datagram receipt.

Must be backported to 2.6.
diff --git a/src/quic_sock.c b/src/quic_sock.c
index e74e889..8d19756 100644
--- a/src/quic_sock.c
+++ b/src/quic_sock.c
@@ -257,6 +257,7 @@
 	return 1;
 
  err:
+	pool_free(pool_head_quic_dgram, new_dgram);
 	return 0;
 }