Add rilmodem test engine. This engine is an improvement on the rilmodem
test server that allows us to test generic interactions with the
rilmodem driver. Instead of just be able to check content of received/
sent bytes on the rild socket, we can now specify a set of steps for a
test that include interactions with the atom. The step types are
- TST_ACTION_SEND: The harness sends a parcel
- TST_ACTION_CALL: The harness calls a driver function
- TST_EVENT_RECEIVE: The driver sends a parcel
- TST_EVENT_CALL: The driver calls a harness (atom) function
Alfonso Sánchez-Beato