t9501-*.sh: Fix a test failure on Cygwin

t9501-*.sh: Fix a test failure on Cygwin

The first (setup) test attempts to create a file, using the
test_commit function, called 'i can has snapshot?'. On cygwin
(and MinGW) this fails with a "No such file or directory" error.
In order to fix the tests, we simply remove the '?' wildcard
from the name, since the purpose of these tests is not about
creating funny filenames.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>