MemoryHeapBase: ifdef for gingerbread/froyo compatibility

Allow to "revert" by a board config flag the offset member addon
see commit f24c4cd0f20 (aosp change id Ie618fb5c0718e)

This change is required to use overlay based proprietary camera libs
coming from gingerbread and froyo builds.

This change also requires a global cflag named BINDER_COMPAT
because a lot of modules use the MemoryHeap includes

Add this in your BoardConfig.mk :
COMMON_GLOBAL_CFLAGS += -DBINDER_COMPAT

Backported from /#/c/13317/

Change-Id: I2e5c10d3cd9584803dd282aa17650661d6499e5b

Conflicts:

	include/binder/MemoryHeapBase.h
Restore support for glReadPixels screenshot path

This is needed for SGX530/540 GPUs.

This reverts commit 3ca76f416bc8665a97636ca8a2d0128b9da9d92c.

Conflicts:
	services/surfaceflinger/SurfaceFlinger.cpp

Change-Id: I52b29dac9bfe23d1f27bd2fe94db6b9adbcfd900