invocations of LAST_INSERT_ID.

Reding of LAST_INSERT_ID inside stored function wasn't noted by caller,
and no LAST_INSERT_ID_EVENT was issued for binary log.

The solution is to add THD::last_insert_id_used_bin_log, which is much
like THD::last_insert_id_used, but is reset only for upper-level
statements.  This new variable is used to issue LAST_INSERT_ID_EVENT.


mysql-test/r/rpl_insert_id.result:
  For bug#21726, add result for statement-based replication of function
  calls.
mysql-test/t/rpl_insert_id.test:
  For bug#21726, add test case for statement-based replication of function
  calls.
sql/item_func.cc:
  Set THD::last_insert_id_used_bin_log for issuing of LAST_INSERT_ID_EVENT.
sql/log.cc:
  Issue LAST_INSERT_ID_EVENT if THD::last_insert_id_used_bin_log is set.
sql/set_var.cc:
  Set THD::last_insert_id_used_bin_log for issuing of LAST_INSERT_ID_EVENT.
sql/sql_class.cc:
  Initialize THD::last_insert_id_used_bin_log.
  Fix typo, add whitespace.
sql/sql_class.h:
  Add THD::last_insert_id_used_bin_log.
sql/sql_parse.cc:
  Reset THD::last_insert_id_used_bin_log for upper-level statements.
sql/sql_select.cc:
  Set THD::last_insert_id_used_bin_log for issuing of LAST_INSERT_ID_EVENT.