hardware_legacy: allow alternative vibrator implementations

The native vibrator code in libhardware_legacy assumes the vibrator
is always controlled by inputting timers into sysfs (at
/sys/class/timed_output/vibrator/enable). This isn't necessarily true,
there's an upcoming device which has the vibrator controlled by ioctl()

This patch lets the device configuration specify an alternative
vibrator implementation throught the variable BOARD_HAS_VIBRATOR_IMPLEMENTATION

That variable should point to a sourcefile that implements the vibrator
"int sendit(timeout_ms)" function, like this:

BOARD_HAS_VIBRATOR_IMPLEMENTATION := ../../device/vendor/model/vibrator.c

Change-Id: I78d60480f87ef00a0bab096d7f42e47501def936
2 files changed