Add recipe to build for Asus Flip Chromebook

Add recipe to build for Asus Flip Chromebook

This build includes the GPU-specific code (EGL, GLES)

The armhf_sysroot should be generic enough to support
other ARM targets, like the Raspberry Pi.

I split out the EGL dependencies into their own CIPD package
(chromebook_c100p_lib) to facilitate the modularity of the approach.

When we add another ARM chromebook, maybe one that has different libraries,
we should be able to re-use armhf_sysroot and then a newly created CIPD asset for
that specific GPU (if needed).

Maybe this also can be used to build for the chromecasts (thus the TODO)

Bug: skia:
NOTRY=true

Change-Id: Icc131025932dc8d41da5be39f3c5cad0aa95d848
Reviewed-on: https://skia-review.googlesource.com/11064
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Eric Boren <borenet@google.com>