--dirstat: In case of renames, use target filename instead of source filename

--dirstat: In case of renames, use target filename instead of source filename

This changes --dirstat analysis to count "damage" toward the target filename,
rather than the source filename. For renames within a directory, this won't
matter to the final output, but when moving files between diretories, the
output now lists the target directory rather than the source directory.

Signed-off-by: Johan Herland <redacted>
Acked-by: Linus Torvalds <redacted>
Signed-off-by: Junio C Hamano <redacted>