Added handlerton flag to make storage engines invisable via flag.

mysql-test/r/ps_1general.result:
  Remove binlog from visable engine list.
sql/handler.h:
  Added documentation to HTON's
sql/log.cc:
  binlog now has hidden flag show that it does now show up in show storage engine list.
sql/sql_show.cc:
  Flag removes engines from view in show storage engines

mysql-test/r/ps_1general.result

@@ -332,7 +332,6 @@ CSV	YES/NO	CSV storage engine
 ndbcluster	YES/NO	Clustered, fault-tolerant, memory-based tables
 FEDERATED	YES/NO	Federated MySQL storage engine
 MRG_MYISAM	YES/NO	Collection of identical MyISAM tables
-binlog	YES/NO	This is a meta storage engine to represent the binlog in a transaction
 ISAM	YES/NO	Obsolete storage engine
 drop table if exists t5;
 prepare stmt1 from ' drop table if exists t5 ' ;

sql/handler.h

@@ -401,8 +401,9 @@ struct show_table_alias_st {
 /* Possible flags of a handlerton */
 #define HTON_NO_FLAGS                 0
 #define HTON_CLOSE_CURSORS_AT_COMMIT (1 << 0)
-#define HTON_ALTER_NOT_SUPPORTED     (1 << 1)
-#define HTON_CAN_RECREATE            (1 << 2)
+#define HTON_ALTER_NOT_SUPPORTED     (1 << 1) //Engine does not support alter
+#define HTON_CAN_RECREATE            (1 << 2) //Delete all is used fro truncate
+#define HTON_HIDDEN                  (1 << 3) //Engine does not appear in lists
 
 typedef struct st_thd_trans
 {

sql/log.cc

@@ -67,7 +67,7 @@ handlerton binlog_hton = {
   NULL,                         /* create_cursor_read_view */
   NULL,                         /* set_cursor_read_view */
   NULL,                         /* close_cursor_read_view */
-  HTON_NO_FLAGS
+  HTON_HIDDEN
 };
 
 /*

sql/sql_show.cc

@@ -69,6 +69,8 @@ bool mysqld_show_storage_engines(THD *thd)
 
   handlerton **types;
   for (types= sys_table_types; *types; types++)
+  {
+    if (!((*types)->flags & HTON_HIDDEN))
     {
       protocol->prepare_for_resend();
       protocol->store((*types)->name, system_charset_info);
@@ -82,6 +84,7 @@ bool mysqld_show_storage_engines(THD *thd)
       if (protocol->write())
         DBUG_RETURN(TRUE);
     }
+  }
   send_eof(thd);
   DBUG_RETURN(FALSE);
 }