toolchain_build: Refactor package generation to support Canadian cross
toolchain_build: Refactor package generation to support Canadian cross

Use a host identifier in component names for components that run on the
host.  Prepare to have x86 Linux builders cross-build ARM/Linux-hosted
tools.  Actually doing that is disabled for now, pending an upstream
fix for cross-building binutils.

BUG= none
TEST= toolchain trybots
R=bradnelson@google.com, jfb@chromium.org, dschuff@chromium.org

Review URL: https://codereview.chromium.org/101083004

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@12518 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client