Meta::ZeroClickInfo: simplify supported attributes check.

Streamline to a single code path for checking key/value pairs.

The hash key look up will be faster than checking against every
element in the array from the function call each time.

On the other hand, even though I got here somehow, I can't actually see
where it will get run.
@nilnilnil It's assumed that if it's an array we can silently cast it into a HASH where the even-numbered elements are the keys and the odd-numbered elements are the associated values.  This is pretty much how hashes are initialized, too, after all, although generally using a "fat comma" where it makes more sense.

This is the same as the previous code was doing, except that you could have a mis-matched final element.  I can't imagine this was ever intentionally being used, though.