password": additional fix, also make sure that a syntax error is 
returned for set names="foo" when there is no such variable or no
stored procedure.


mysql-test/r/sp-error.result:
  Test results fixed: a new test for Bug#13510
mysql-test/t/sp-error.test:
  A new test for Bug#13510 (set names out of an SP)
sql/sql_yacc.yy:
  Bug#13510: fix the case when there is no stored procedure or
  no 'names' variable declared. Return a syntax error in this case.