User name (host name) has limit on length. The server code relies on these
limits when storing the names. The problem was that sometimes these limits
were not checked properly, so that could lead to buffer overflow.
  
The fix is to check length of user/host name in parser and if string is too
long, throw an error.


mysql-test/r/grant.result:
  Updated result file.
mysql-test/r/sp.result:
  Updated result file.
mysql-test/r/trigger.result:
  Updated result file.
mysql-test/r/view.result:
  Updated result file.
mysql-test/t/grant.test:
  Added test for BUG#16899.
mysql-test/t/sp.test:
  Added test for BUG#16899.
mysql-test/t/trigger.test:
  Added test for BUG#16899.
mysql-test/t/view.test:
  Added test for BUG#16899.
sql/mysql_priv.h:
  Added prototype for new function.
sql/sql_acl.cc:
  Remove outdated checks.
sql/sql_parse.cc:
  Add a new function for checking string length.
sql/share/errmsg.txt:
  Added new resources.
sql/sql_yacc.yy:
  Check length of user/host name.