libgui: add support for Samsung external gralloc usecases

Taken from insignal:
http://git.insignal.co.kr/insignal/arndale_octa-jb_mr1.1/android/platform/frameworks/native/commit/?h=arndale_octa-jb_mr1.1&id=4695f276a4dd642056653eca1431b0b9137088bf

Change-Id: I3113304bb92d076b723b98185674759df487a93a