This also adds a new "AUTO_GOPATH" environment variable that will create an appropriate GOPATH as part of the build process.
Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Upstream-commit: d3d85d38fb5bdd0327fdc9fe8b637cb0f4e1dcf2
Component: engine