Adds a new overlay driver which uses multiple lower directories to create the union fs.
Additionally it uses symlinks and relative mount paths to allow a depth of 128 and stay within the mount page size limit.
Diffs and done directly over a single directory allowing diffs to be done efficiently and without the need fo the naive diff driver.
Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
Upstream-commit: 23e5c94cfb26eb72c097892712d3dbaa93ee9bc0
Component: engine
c6851cb49f