The problem is that the one phase commit function failed to
properly end a empty transaction. The solution is to ensure
that the transaction cleanup procedure is invoked even for
empty transactions.

mysql-test/r/xa.result:
  Add test case result for Bug#45548
mysql-test/t/xa.test:
  Add test case for Bug#45548
sql/handler.cc:
  Invoke transaction cleanup function whenever a transaction is ended.