Add relay crypto mock points for tests.

Co-authored-by: George Kadianakis <desnacked@riseup.net>

src/core/or/relay.c

@@ -355,11 +355,11 @@ circuit_receive_relay_cell(cell_t *cell, circuit_t *circ,
  *  - Encrypt it to the right layer
  *  - Append it to the appropriate cell_queue on <b>circ</b>.
  */
-static int
-circuit_package_relay_cell(cell_t *cell, circuit_t *circ,
+MOCK_IMPL(int,
+circuit_package_relay_cell, (cell_t *cell, circuit_t *circ,
                            cell_direction_t cell_direction,
                            crypt_path_t *layer_hint, streamid_t on_stream,
-                           const char *filename, int lineno)
+                           const char *filename, int lineno))
 {
   channel_t *chan; /* where to send the cell */
 

src/core/or/relay.h

@@ -78,6 +78,11 @@ void destroy_cell_queue_append(destroy_cell_queue_t *queue,
 void channel_unlink_all_circuits(channel_t *chan, smartlist_t *detached_out);
 MOCK_DECL(int, channel_flush_from_first_active_circuit,
           (channel_t *chan, int max));
+MOCK_DECL(int, circuit_package_relay_cell, (cell_t *cell, circuit_t *circ,
+                           cell_direction_t cell_direction,
+                           crypt_path_t *layer_hint, streamid_t on_stream,
+                           const char *filename, int lineno));
+
 void update_circuit_on_cmux_(circuit_t *circ, cell_direction_t direction,
                              const char *file, int lineno);
 #define update_circuit_on_cmux(circ, direction) \