MDEV-4549 [PATCH] Clean up code working with ACL tables

* enum values to index different ACL tables, instead of hard-coded numbers
  (even different in diffent functions).
* move TABLE_LIST initialization into open_grant_tables()
  and use it everywhere
* change few my_bool's to bool's

Author: vuvova

mysql-test/r/not_embedded_server.result

@@ -1,4 +1,4 @@
-call mtr.add_suppression("Can't open and lock privilege tables: Table 'host' was not locked with LOCK TABLES");
+call mtr.add_suppression("Can't open and lock privilege tables: Table 'user' was not locked with LOCK TABLES");
 SHOW VARIABLES like 'slave_skip_errors';
 Variable_name	Value
 slave_skip_errors	OFF
@@ -16,7 +16,7 @@ DROP TABLE IF EXISTS t1;
 CREATE TABLE t1 (c1 INT);
 LOCK TABLES t1 READ;
 FLUSH PRIVILEGES;
-ERROR HY000: Table 'host' was not locked with LOCK TABLES
+ERROR HY000: Table 'user' was not locked with LOCK TABLES
 UNLOCK TABLES;
 DROP TABLE t1;
 #

mysql-test/r/sp-destruct.result

@@ -128,11 +128,8 @@ CREATE FUNCTION f1() RETURNS INT RETURN 1;
 RENAME TABLE mysql.procs_priv TO procs_priv_backup;
 FLUSH TABLE mysql.procs_priv;
 DROP FUNCTION f1;
-ERROR 42S02: Table 'mysql.procs_priv' doesn't exist
 SHOW WARNINGS;
 Level	Code	Message
-Error	1146	Table 'mysql.procs_priv' doesn't exist
-Warning	1405	Failed to revoke all privileges to dropped routine
 # Restore the procs_priv table
 RENAME TABLE procs_priv_backup TO mysql.procs_priv;
 FLUSH TABLE mysql.procs_priv;

mysql-test/t/not_embedded_server.test

@@ -6,7 +6,7 @@
 
 # End of 4.1 tests
 
-call mtr.add_suppression("Can't open and lock privilege tables: Table 'host' was not locked with LOCK TABLES");
+call mtr.add_suppression("Can't open and lock privilege tables: Table 'user' was not locked with LOCK TABLES");
 
 #
 # Bug#43835: SHOW VARIABLES does not include 0 for slave_skip_errors

mysql-test/t/sp-destruct.test

@@ -214,7 +214,6 @@ RENAME TABLE mysql.procs_priv TO procs_priv_backup;
 FLUSH TABLE mysql.procs_priv;
 
 # DROP FUNCTION used to cause an assert.
---error ER_NO_SUCH_TABLE
 DROP FUNCTION f1;
 SHOW WARNINGS;