Split sub-crates under crosvm root directory into several independent
workspaces for adding ebuild files for those crates.
data_model and sys_util could only be built by emerge after creating
their ebuilds.
BUG=chromium:916921
TEST='emerge-eve crosvm'
TEST=Run 'cargo build' under crosvm directory
Change-Id: I2dddbbb7c7344e643183a5885e867f134b299591
Reviewed-on: https://chromium-review.googlesource.com/1385972
Commit-Ready: Chih-Yang Hsia <paulhsia@chromium.org>
Tested-by: Chih-Yang Hsia <paulhsia@chromium.org>
Reviewed-by: Chirantan Ekbote <chirantan@chromium.org>
Reviewed-by: Zach Reizner <zachr@chromium.org>