We're only using it to distribute files in case of failure, which isn't
well supported currently, but can be handled for now by using the
DIST_DIR environment variable during the command execution.
This was at least one cause that we'd be re-running Soong during every
build server build, as the DIST_DIR values are unique.
Test: m dist
Change-Id: Ibd5e6b6c46695350de80b745bfb6a6aa685033a0
2d31a44b8a