hw/input/goldfish_events.c: Implement goldfish events device

Implement the goldfish 'events' device which provides a variety
of input events including simulated touchscreen and hard buttons.

This is a forward port and revamp of the goldfish/events_device
from the classic Android emulator. Some features from the
classic emulator are not supported:
 * multitouch
 * full keyboard

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
hw/arm/ranchu: Add goldfish events device

Add the goldfish events device to the ranchu board.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Merge remote-tracking branch 'peter/ranchu' into ranchu

Conflicts:
	hw/arm/ranchu.c
	hw/input/goldfish_events.c
android_pipe.c: fixup debug prints to use portable formats