Even more warning fixes

[Jamey Sharp]

On Fri, Nov 12, 2010 at 10:06 AM, Jamey Sharp <jamey at minilop.net> wrote:
> For patches 2-4:
> Reviewed-by: Jamey Sharp <jamey at minilop.net>

Oh, wait. You don't need the conditionals or the lookup_ret variable
here at all: the result pointer is already guaranteed to be NULL if
the return value is not Success.

I guess I'm willing to stick my reviewed-by on these warning fixes
either way, but I'd prefer to not add the unnecessary checks.

Also, you might consider casting the first argument of
dixLookupResourceBy* to (pointer*), rather than (pointer). The
compiler doesn't care since they're both compatible with (void*), but
(pointer*) is better documentation.

Jamey