--added ability to obtain plugin variables from my.cnf on INSTALL PLUGIN stage
--option 'ignore-builtin-innodb' disables all InnoDB builtin plugins
  (including I_S plugins)


sql/mysql_priv.h:
  --added ability to obtain plugin variables from my.cnf on INSTALL PLUGIN stage
sql/mysqld.cc:
  --added ability to obtain plugin variables from my.cnf on INSTALL PLUGIN stage
sql/sql_plugin.cc:
  --added ability to obtain plugin variables from my.cnf on INSTALL PLUGIN stage
  --option 'ignore-builtin-innodb' disables all InnoDB builtin plugins
    (including I_S plugins)