Fix for bug #13025; Server crash in filesort because wrong call to handler::position()


client/mysqltest.c:
  Code cleanup during review
mysql-test/r/innodb.result:
  Added test case for bug #13025; Server crash in filesort because wrong call to handler::position()
mysql-test/t/innodb.test:
  Added test case for bug #13025; Server crash in filesort because wrong call to handler::position()
sql/filesort.cc:
  Don't call handler::position() if row was not found
sql/item_cmpfunc.cc:
  Indentation changes
sql/sql_select.cc:
  Moved variable to outer level