Resolve engine_process_key_event trouble

[onting]

The engine has bug in _process_key_event function.
It must be related with ic_process and am_push.

GDB can attach specific running process to itself for inspection.
This issue can be handled in this way.
First, compile the engine with -g option and install it to your system.
Second, run it with 'ibus engine hanjp' command.
Third, run 'pid -p engine-pid'.
Last, inspect _process_key_event by adding some conditional break points.