bzr push into mysql-6.0 branch (staale.smedseng:2937 to 2938) Bug#22891

[Staale Smedseng]

 2938 Staale Smedseng	2008-11-20 [merge]
      A fix for Bug#22891 "session level max_allowed_packet can be
      set but is ignored".
                                        
      This patch makes @@session.max_allowed_packed and
      @@session.net_buffer_length read-only as suggested in the bug
      report. The user will have to use SET GLOBAL (and reconnect)
      to alter the session values of these variables.
                                  
      The error string ER_VARIABLE_IS_READONLY is introduced.
                                  
      Tests are modified accordingly.
      
      Merge into mysql-6.0-bugteam.

 2937 Staale Smedseng	2008-11-20
      A fix for Bug#22891 "session level max_allowed_packet can be
      set but is ignored".
                                        
      This patch makes @@session.max_allowed_packed and
      @@session.net_buffer_length read-only as suggested in the bug
      report. The user will have to use SET GLOBAL (and reconnect)
      to alter the session values of these variables.
                                  
      The error string ER_VARIABLE_IS_READONLY is introduced.
                                  
      Tests are modified accordingly.
modified:
  mysql-test/r/debug_sync.result
  mysql-test/r/func_compress.result
  mysql-test/r/locktrans_innodb.result
  mysql-test/r/locktrans_myisam.result
  mysql-test/r/max_allowed_packet_basic.result
  mysql-test/r/max_allowed_packet_func.result
  mysql-test/r/net_buffer_length_basic.result
  mysql-test/r/packet.result
  mysql-test/r/union.result
  mysql-test/r/variables.result
  mysql-test/suite/backup/r/backup_backupdir.result
  mysql-test/suite/rpl/r/rpl_locktrans_myisam.result
  mysql-test/t/func_compress.test
  mysql-test/t/innodb_bug34300.test
  mysql-test/t/max_allowed_packet_basic.test
  mysql-test/t/max_allowed_packet_func.test
  mysql-test/t/net_buffer_length_basic.test
  mysql-test/t/packet.test
  mysql-test/t/union.test
  mysql-test/t/variables.test
  sql/set_var.cc
  sql/set_var.h
  sql/share/errmsg.txt