The special TRUNCATE TABLE (DDL) transaction wasn't being properly
rolled back if a error occurred during row by row deletion. The
error can be caused by a foreign key restriction imposed by InnoDB
SE and would cause the server to erroneously issue a implicit
commit.

The solution is to rollback the transaction if a truncation via row
by row deletion fails, otherwise commit. All effects of a TRUNCATE 
ABLE operation are rolled back if a row by row deletion fails.

mysql-test/include/commit.inc:
  Truncate always starts a transaction and commits at the end.
  The commit at the end increases the count by two, one is the
  storage engine commit and the other is the binary log.
mysql-test/r/commit_1innodb.result:
  Update test case results.
mysql-test/r/innodb_mysql.result:
  Update test case results.
mysql-test/t/innodb_mysql.test:
  Add test case for Bug#37016
sql/sql_delete.cc:
  Move truncation using row by row deletion to its own function.
  If row by row deletion fails, rollback the transaction.
  
  Remove the meddling with disabling and enabling of autocommit
  as TRUNCATE transaction is now explicitly ended (committed
  or rolled back).