make 'use database' okay.

The problem was that we didn't check stored-routine privileges
in check_grant_db().

The patch adds this check.


mysql-test/r/grant.result:
  Update result file.
mysql-test/r/sp-security.result:
  Update result fil.
mysql-test/t/grant.test:
  Added test case for BUG#9504.
mysql-test/t/sp-security.test:
  Update test.
sql/sql_acl.cc:
  Check stored routines privileges.