t/test.sh: Fix a test for 'split' on solaris

t/test.sh: Fix a test for 'split' on solaris

When looking at output from a test run on Solaris, one test in the
'split' suite showed up as OK but was actually showing a diff
invocation error.

The -q argument (for quiet) does not exist on the version of diff that
is installed on Solaris. Since wvtest intercepts output from tested
commands, the -q argument is actually not needed. Remove the argument in
order to make the test execute correctly under all operating systems
that were tested thus far.

Signed-off-by: Gabriel Filion <lelutin@gmail.com>