Adjust the check that defines the error message to be returned.


mysql-test/r/sp-error.result:
  Update results (more accurate error code)
mysql-test/r/sp-prelocking.result:
  Update results (more accurate error code)
mysql-test/r/trigger.result:
  Update results (more accurate error code)
mysql-test/t/sp-error.test:
  ER_NOT_LOCKED -> ER_NO_SUCH_TABLE
mysql-test/t/sp-prelocking.test:
  Add a test case for Bug#27907
mysql-test/t/trigger.test:
  ER_NOT_LOCKED -> ER_NO_SUCH_TABLE
sql/sql_base.cc:
  Adjust the check for where-we-are for a better error message.