enable RTS write

This allows for correct time in recovery.
shift to XZ compression/decompression
use ccache to speed up building between cleanups
fix for toolchain GCC 4.7 Google
updated build scipts to use toolchain GCC 4.7 google
msm: mdp: Fix reserved field usage

An earlier commit(ec5b2f)increased the number of reserved fields
in the kernel standard fb.h header changing the struct size.
This caused issues with userland applications using the corresponding
bionic header. This patch revert the earlier increas in size
and makes corresponding adjustments to the reserved field usage.
A follow up patch will remove usage of reserved fields entirely.
added optimizations for compiling (thanks to @franciscofranco)