Merge branch 'yc/histogram-hunk-shift-fix' into jch

The final clean-up phase of the diff output could turn the result of
histogram diff algorithm suboptimal, which has been corrected.

Comments?

* yc/histogram-hunk-shift-fix:
  xdiff: re-diff shifted change groups when using histogram algorithm

diff --cc t/meson.build
Simple merge

diff --cc xdiff/xdiffi.c
Simple merge