Corrective patch to fix test failures in pushbuild and add assertions
to help debug rpl_extraColmaster test failures.


mysql-test/extra/rpl_tests/rpl_row_tabledefs.test:
  WL#3915 : (NDB) master's cols > slave
  
  Change test to omit the port numbers in the result file.
mysql-test/suite/rpl/r/rpl_row_tabledefs_2myisam.result:
  WL#3915 : (NDB) master's cols > slave
  
  Corrected result file.
mysql-test/suite/rpl/r/rpl_row_tabledefs_3innodb.result:
  WL#3915 : (NDB) master's cols > slave
  
  Corrected result file.
sql/rpl_utility.cc:
  WL#3915 : (NDB) master's cols > slave
  
  Added assertions to assist in debugging.