Remove unnecessary !!(expressions)

_Bool already does that.

Signed-off-by: Ran Benita <ran234@gmail.com>
x11: don't iterate on empty batches

If count % SIZE == 0 we did a useless iteration where start==stop. It's
harmless but strange, so don't do that.

Signed-off-by: Ran Benita <ran234@gmail.com>