diff: add -I<regex> that ignores matching changes

[git] / t / t4013 / diff.diff-tree_-c_--stat_--summary_side

$ git diff-tree -c --stat --summary side
c7a2ab9e8eac7b117442a607d5a9b3950ae34d5a
 dir/sub | 2 ++
 file0   | 3 +++
 file3   | 4 ++++
 3 files changed, 9 insertions(+)
 create mode 100644 file3
$