We'd like to use buildhistory more during patch review however its
proving hard, particularly where whole subtrees of files move,
such as a kernel version upgrade, or where a software module moves
include directory.
This adds file rename matching which covers our common case of library
moves, kernel upgrades and more.
A new test case is also added so that someone in the future can change
the code and test the logic is still doing the expected things.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
