Integer division already had this modification, to avoid
division by 0, but integer modulo hadn't been modified
to match the other fix, which is now done here.

Bug chromium:763435

Change-Id: I40f4ed9f1c4b5889ddf47abc1bb7c70c21cbd7b8
Reviewed-on: https://swiftshader-review.googlesource.com/12908Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Alexis Hétu <sugoi@google.com>