The next number (AUTO_INCREMENT) field of the table for write
rows events are not initialized, and cause some engines (innodb)
not correctly update the tables's auto_increment value.

This patch fixed this problem by honor next number fields if present.

mysql-test/extra/rpl_tests/rpl_auto_increment.test:
  Add test code for BUG#41986
mysql-test/suite/rpl/r/rpl_auto_increment.result:
  update test result file for BUG#41986
sql/log_event.cc:
  set next_number_field before writing rows, and reset next_number_field after finished writing rows