disable test cases for bugs not fixed in xtradb.

mysql-test/suite/innodb/t/innodb-lock.test:
  instead of disabling the test in disabled.def
  (hoping that somebody someday will enable it),
  skip it only for xtradb (not for innodb), and
  only for the current xtradb version. the test
  will enable itself automatically on the next
  xtradb merge
mysql-test/suite/innodb/t/innodb_cmp_drop_table.test:
  instead of disabling the test in disabled.def
  (hoping that somebody someday will enable it),
  skip it only for xtradb (not for innodb), and
  only for the current xtradb version. the test
  will enable itself automatically on the next
  xtradb merge
mysql-test/suite/innodb/t/innodb_corrupt_bit.test:
  fix the error number
storage/innobase/handler/ha_innodb.cc:
  fix the error number
storage/xtradb/handler/ha_innodb.cc:
  fix the error number