Reason:
=======
Race condition between btr_search_drop_hash_index() and
btr_search_lazy_free(). One thread does resizing of buffer pool
and clears the ahi on all pages in the buffer pool, frees the
index and table while removing the last reference. At the same time,
other thread access index->heap in btr_search_drop_hash_index().

Solution:
=========
Acquire the respective ahi latch before checking index->freed()

btr_search_drop_page_hash_index(): Added new parameter to indicate
that drop ahi entries only if the index is marked as freed

btr_search_check_marked_free_index(): Acquire all ahi latches and
return true if the index was freed