Make STMT replication default for 5.1.
Add a default of MIXED into the config files
Fix the tests that needed MIXED replication mode.

mysql-test/include/mix1.inc:
  Bug #39812: Fix the tests that needed MIXED replication mode.
mysql-test/r/innodb-semi-consistent.result:
  Bug #39812: Fix the tests that needed MIXED replication mode.
mysql-test/r/innodb.result:
  Bug #39812: Fix the tests that needed MIXED replication mode.
mysql-test/r/innodb_mysql.result:
  Bug #39812: Fix the tests that needed MIXED replication mode.
mysql-test/r/tx_isolation_func.result:
  Bug #39812: Fix the tests that needed MIXED replication mode.
mysql-test/t/innodb-semi-consistent.test:
  Bug #39812: Fix the tests that needed MIXED replication mode.
mysql-test/t/innodb.test:
  Bug #39812: Fix the tests that needed MIXED replication mode.
mysql-test/t/tx_isolation_func.test:
  Bug #39812: Fix the tests that needed MIXED replication mode.
sql/mysqld.cc:
  Bug #39812: Make STMT replication default for 5.1.
support-files/my-huge.cnf.sh:
  Bug #39812: Add a default of MIXED into the config files
support-files/my-innodb-heavy-4G.cnf.sh:
  Bug #39812: Add a default of MIXED into the config files
support-files/my-large.cnf.sh:
  Bug #39812: Add a default of MIXED into the config files
support-files/my-medium.cnf.sh:
  Bug #39812: Add a default of MIXED into the config files
support-files/my-small.cnf.sh:
  Bug #39812: Add a default of MIXED into the config files