- Don't omit the @@debug variable from testcase check, since it can cause real problems.
 - Fix some bad merges by reverting to be identical to MySQL 5.1.

mysql-test/include/mtr_check.sql:
  Don't omit the @@debug variable from testcase check, since it can cause real problems.
mysql-test/r/mysqlbinlog_row_big.result:
  Fix incorrect merge.
mysql-test/r/variables-big.result:
  Fix incorrect merge, by reverting to MySQL 5.1 version.
mysql-test/t/mysqlbinlog_row_big.test:
  Fix incorrect merge.
mysql-test/t/variables-big.test:
  Fix incorrect merge, by reverting to MySQL 5.1 version.