Fix t0061 test for windows

Replace test_cmp with test_cmp_text to avoid LF/CRLF confusion.

The cat from msysgit, version 2.0, is very different from the current one which
is version 5.97.

It lloks like as http://git.savannah.gnu.org/gitweb/?p=coreutils.git;a=commit;h=8770c00ef45e3c6c4dd3d5ce1e55a6fb1adb13dc is responsible for the change.

Signed-off-by: Thomas Braun <thomas.braun@virtuell-zuhause.de>