skipDelete  - delete an item.
       #include <util/skiplist.h>
       void skipDelete(skipList list, UINT32 key);
       list - list to delete item from.
       key - key identifying value to delete.
       Delete the item associated with <key> from <list>.
       MT-Level: Safe if <list> thread-safe.
       None.
       skipDelete(3),    skipFreeList(3),    skipRelease(3),    skipInsert(3),
       skipSearch(3), skipNext(3), skipNewList