libgralloc: update and clean up

Change-Id: Id54af3d73f9fc9eff4915f54c5fc0f87b72042c7
hwcomposer: update to hwcomposer 1.0 API

Dummy functions borrowed from: https://github.com/trevd/android_hardware_broadcom_bcm2708

Change-Id: I7d2d5d3c16a0b55b48407297556a64092c50b0ae