Fix /me always returning error, even on correct delivery

According to the Toxcore API, failed actions return 0, succesful actions another number.

https://libtoxcore.so/api/tox_8h.html#a446bfa17062465c7f18674e9ff559f8c

This fixes a /me sent from tox-prpl always displaying "Message failed to sent" in Pidgin, even though it arrives correctly.