In some cases for cache purpoes we not only need to know which file
is going to be used but also which paths were considered. Add a
localpaths method which includes the history.
The core which() funciton already supports this, this just extends
the function to preserve the extra data we need. localpath becomes
just a special case of the case with history.
(Bitbake rev: d71407dbbf82659f245e002ecaad02b26838f455)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>