Added new test case for dropping column on the end of master table


mysql-test/extra/rpl_tests/rpl_extraSlave_Col.test:
  Added new test case for dropping column on the end of master table
mysql-test/r/rpl_extraCol_innodb.result:
  Added new test case for dropping column on the end of master table
mysql-test/r/rpl_extraCol_myisam.result:
  Added new test case for dropping column on the end of master table
mysql-test/r/rpl_ndb_extraCol.result:
  Added new test case for dropping column on the end of master table