Fix multiple debugger issues. (#1640)

- Wait for free byte code pointers during garbage collection.
- Detect incorrect free requests in the debugger server.
- Ignore byte code blocks loaded from snapshot.
- Use memmove instead of memcpy to avoid receive buffer corruption.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

jerry-core/debugger/jerry-debugger-ws.c

@@ -551,9 +551,9 @@ jerry_debugger_receive (void)
 
     if (message_total_size < offset)
     {
-      memcpy (recv_buffer_p,
-              recv_buffer_p + message_total_size,
-              offset - message_total_size);
+      memmove (recv_buffer_p,
+               recv_buffer_p + message_total_size,
+               offset - message_total_size);
     }
 
     JERRY_CONTEXT (debugger_receive_buffer_offset) = (uint16_t) (offset - message_total_size);