This change introduces API's in gralloc to allow clients
to synchronize with framebuffer posts.
CRs-fixed: 348953
(cherry picked from commit f81de75b1adb78018c0bd54b7f27901ba467defd)
Conflicts:
libgralloc/framebuffer.cpp
libqcomui/qcom_ui.h
Change-Id: I98b6a2b3243f520138cb5d1c76493cdfa3af60b6