tests: check --[short]stat output after chmod
tests: check --[short]stat output after chmod

Add a test to check 'diff --stat' output with a text file after chmod,
and the same for a binary file. This demonstrates that text and binary
files are treated differently, which can be misleading.

While at it, add tests to check --shortstat output, too.

Reported-by: Martin Mareš <df2fa7c39d141dc5dc5589fed74180e757ed6c9a@ucw.cz>
Signed-off-by: Zbigniew Jędrzejewski-Szmek <1a002461b1932d3892b64879e6e8987274fa7074@in.waw.pl>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git