Add traces to systrace when binder tracing is enabled

If binder tracing is enabled, we also output the class/method name
to systrace. This is the first step toward a system in which we could
show the full stack trace in systrace.

Test:
adb shell am trace-ipc start
python systrace.py
adb shell am trace-ipc stop

Change-Id: I6d0354c9560c4518c84fb3fdb66219b460e69f67