Fixed a compiler dependent expression to be more portable.
Initialized 'dummy' in construct_help_options() so that loaded
plugin show themselves as TRUE in the help output.


mysys/hash.c:
  WL#2936 - Falcon & MySQL plugin interface: server variables
  Fixed a compiler dependent expression to be more portable.
sql/handler.cc:
  WL#2936 - Falcon & MySQL plugin interface: server variables
  Added a DBUG_PRINT.
sql/sql_plugin.cc:
  WL#2936 - Falcon & MySQL plugin interface: server variables
  Initialized 'dummy' in construct_help_options() so that loaded
  plugin show themselves as TRUE in the help output.
  Fixed a DBUG_ENTER, added a DBUG_PRINT.
  Added comments.