pixelflinger: back-port AOSP master version.

Pixelflinger doesn't have an x86 JIT, and the generic scanline()
routine is _extremely_ slow. This makes UI performance very slow.
when running full_x86-eng under emulation.

This patch back-ports the AOSP master pixelflinger into the
gingerbread branch. This essentially contains more than a dozen
new "shortcut" scanline functions used to speed-up the pixel
operations that are mostly used with the normal widget UI.

GL applications (e.g. Gallery3D) will still be very slow, but
this makes the home screen, app launcher, settings and many
simple applications work with very usable performance.

Change-Id: Ia64d8dd2e46820f07e98c4c9a4ec831b59fc61e4