Manifest files containing the same duplicated prefix are wasteful on space
and ultimately this costs build time. Drop the WORKDIR prefix from the manifest
files since this small change mounts up a lot.
(From OE-Core rev: 1cb245a99762e21a170b6a9beabb07e558424946)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>