Add back support for glReadPixels screenshot path.

Thanks to @rmcc and @Hashcode for doing this with KitKat, I just adapted it to Lollipop here.
[2/2] Speed up booting on multicore devices.

Add multithreading support.

Change-Id: I13630de9d75d13c0368d261b3564b787067b65b1

Conflicts:
	cmds/installd/installd.c