Refactor: libpacemaker: Clean up and rename crm_rule_check()

This is a static function; rename to eval_rule().

Replace goto with free() and freeXpathObject() where needed. There are
only two pointers that ever need to be freed.

Rename "max" variable to the more obvious "num_results".

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>