A gralloc extra HAL to retrive buffer detail information.

WHAT IT DOES?
=============
libgralloc_extra.so provide a convenience API for retriving the buffer_t
information, such as width, height, real format, raw buffer handle and more
extra share space for MTK's HWC, Video, and Camera.

HOW IT WAS BUILT?
==================
It needs the following library from AOSP:
1.  libhardware
2.  libcutils
3.  libutils

HOW TO USE IT?
==============
See the usage of gralloc_extra_* at ./tests/
gralloc_test.cpp