MDEV-4816: rpl.rpl_trunc_temp fails in 10.0-serg

Temorary fix for a number of replication tests (rpl.rpl_temp_table_mix_row 
rpl.rpl_trunc_temp rpl.rpl_current_user rpl.rpl_gtid_master_promote):

- THD::decide_logging_format() should not assume that mysql.gtid_slave_pos is 
  a non-replicated table. This used to cause unintended behavior for COMMIT 
  statement: replication would switch to row-based, etc.

The question of what should be done when a user issues a statement that
explicitly modifies mysql.gtid_slave_pos table remains open.

sql/rpl_gtid.cc

@@ -210,6 +210,7 @@ rpl_slave_state::truncate_state_table(THD *thd)
   {
     table= tlist.table;
     table->no_replicate= 1;
+    table->s->is_gtid_slave_pos= TRUE; // TEMPORARY CODE
     err= table->file->ha_truncate();
 
     if (err)
@@ -346,6 +347,7 @@ rpl_slave_state::record_gtid(THD *thd, const rpl_gtid *gtid, uint64 sub_id,
     goto end;
 
   table->no_replicate= 1;
+  table->s->is_gtid_slave_pos= TRUE; // TEMPORARY CODE
   if (!in_transaction)
     thd->variables.option_bits&=
       ~(ulonglong)(OPTION_NOT_AUTOCOMMIT|OPTION_BEGIN);

sql/sql_class.cc

@@ -5001,7 +5001,7 @@ int THD::decide_logging_format(TABLE_LIST *tables)
       DBUG_PRINT("info", ("table: %s; ha_table_flags: 0x%llx",
                           table->table_name, flags));
 
-      if (table->table->no_replicate)
+      if (table->table->no_replicate && !table->table->s->is_gtid_slave_pos)
       {
         /*
           The statement uses a table that is not replicated.

sql/table.cc

@@ -315,6 +315,8 @@ TABLE_SHARE *alloc_table_share(const char *db, const char *table_name,
     strmov(share->path.str, path);
     share->normalized_path.str=    share->path.str;
     share->normalized_path.length= path_length;
+    /* TEMPORARY FIX: if true, this means this is mysql.gtid_slave_pos table */
+    share->is_gtid_slave_pos= FALSE;
     share->table_category= get_table_category(& share->db, & share->table_name);
     share->set_refresh_version();
     share->open_errno= ENOENT;

sql/table.h

@@ -644,6 +644,8 @@ struct TABLE_SHARE
   LEX_STRING normalized_path;		/* unpack_filename(path) */
   LEX_STRING connect_string;
 
+  bool is_gtid_slave_pos;
+
   /* 
      Set of keys in use, implemented as a Bitmap.
      Excludes keys disabled by ALTER TABLE ... DISABLE KEYS.