Fix typo in processbuffer() - tcpdns vs tlsdns

The processbuffer() would call isc__nm_tcpdns_processbuffer() instead of
isc__nm_tlsdns_processbuffer() for the isc_nm_tlsdnssocket type of
socket.

lib/isc/netmgr/netmgr.c

@@ -1857,7 +1857,7 @@ processbuffer(isc_nmsocket_t *sock) {
 	case isc_nm_tcpdnssocket:
 		return (isc__nm_tcpdns_processbuffer(sock));
 	case isc_nm_tlsdnssocket:
-		return (isc__nm_tcpdns_processbuffer(sock));
+		return (isc__nm_tlsdns_processbuffer(sock));
 	default:
 		INSIST(0);
 		ISC_UNREACHABLE();

lib/isc/netmgr/tlsdns.c

@@ -276,6 +276,7 @@ tlsdns_connect_cb(uv_connect_t *uvreq, int status) {
 	return;
 
 error:
+	sock->tls.pending_req = NULL;
 	isc__nm_failed_connect_cb(sock, req, result);
 }