Problem :
---------
While selecting from INFORMATION_SCHEMA.INNODB_CMPMEM with option
big-tables=1, the fetched rows are filled into temp table by the
sql function schema_table_store_record().

Innodb i_s_cmpmem_fill_low() calls the record store callback while
holding buf_pool_mutex. The issue started occurring when we started
to use InnoDB intrinsic table to store the records instead of heap
engine. We re-enter InnoDB to insert record into intrinsic table
while holding buf_pool_mutex and hit ASSERT.

Solution :
----------
Acquire buf_pool_mutex and store records locally and call the store
callback after releasing buf_pool_mutex.

Reviewed-by: Marko Makela <marko.makela@oracle.com>

RB: 10339