by simply disallowing alter procedure/function in an SP (as for drop).


mysql-test/r/sp-error.result:
  Added test case for BUG#7047.
mysql-test/t/sp-error.test:
  Added test case for BUG#7047.
sql/share/errmsg.txt:
  Modified error message for "update procedure/function" too.
sql/sql_yacc.yy:
  Don't allow alter procedure/function in an SP.