Disable Google's home-key handling code

This might be temporary. Upstream now includes multi-behavior key
handling for HOME, which conflicts with our own code when running
in parallel, resulting in funky behaviors. Since the CM implementation
is more flexible, let's keep that for the time being and disable
Google's; It might be a good idea to rewrite our version so that it's
an extension of theirs, though.

Change-Id: I5d55301772607315b410880c1194a0076e21cb80
hwui: Don't discard framebuffer on exynos4

The layers gets empty/not cleaned and redrawn on top of the preview,
causing beautiful glitch on homescreen, and drawing black instead
of transparency.

Change-Id: I633b104224c73c625f1193ee3dde41823cddc5bf
Merge remote-tracking branch 'cm/cm-10.2' into dc43