tables requires privileges for them if some table or column level grants
present" (with after-review fixes).

We should set SELECT_ACL for implicitly opened tables in 
my_tz_check_n_skip_implicit_tables() to be able to bypass privilege
checking in check_grant(). Also we should exclude those tables from
privilege checking in multi-update.


mysql-test/r/timezone2.result:
  Extended test for bug #6116 "SET time_zone := ... requires access to
  mysql.time_zone tables"
  Added test for bug #6765 "Implicit access to time zone description 
  tables requires privileges for them if some table or column level grants
  present"
mysql-test/t/timezone2.test:
  Extended test for bug #6116 "SET time_zone := ... requires access to
  mysql.time_zone tables"
  Added test for bug #6765 "Implicit access to time zone description 
  tables requires privileges for them if some table or column level grants
  present"
sql/item_geofunc.cc:
  sql_acl.h is now included via mysql_priv.h
sql/item_strfunc.cc:
  sql_acl.h is now included via mysql_priv.h
sql/log.cc:
  sql_acl.h is now included via mysql_priv.h
sql/mysql_priv.h:
  Now we have to include sql_acl.h before tztime.h, since 
  my_tz_check_n_skip_implicit_tables() defined there requires
  SELECT_ACL constant defined in sql_acl.h.
sql/mysqld.cc:
  sql_acl.h is now included via mysql_priv.h
sql/repl_failsafe.cc:
  sql_acl.h is now included via mysql_priv.h
sql/set_var.cc:
  sql_acl.h is now included via mysql_priv.h
sql/sql_acl.cc:
  sql_acl.h is now included via mysql_priv.h
sql/sql_base.cc:
  sql_acl.h is now included via mysql_priv.h
sql/sql_cache.cc:
  sql_acl.h is now included via mysql_priv.h
sql/sql_class.cc:
  sql_acl.h is now included via mysql_priv.h
sql/sql_db.cc:
  sql_acl.h is now included via mysql_priv.h
sql/sql_derived.cc:
  sql_acl.h is now included via mysql_priv.h
sql/sql_do.cc:
  sql_acl.h is now included via mysql_priv.h
sql/sql_insert.cc:
  sql_acl.h is now included via mysql_priv.h
sql/sql_parse.cc:
  check_one_table_access(): Tweaked comments.
  multi_update_precheck(): Added skipping of implicitly opened tables
    during privilege checking.
sql/sql_prepare.cc:
  sql_acl.h is now included via mysql_priv.h
sql/sql_repl.cc:
  sql_acl.h is now included via mysql_priv.h
sql/sql_show.cc:
  sql_acl.h is now included via mysql_priv.h
sql/sql_update.cc:
  sql_acl.h is now included via mysql_priv.h
sql/sql_yacc.yy:
  sql_acl.h is now included via mysql_priv.h
sql/tztime.h:
  my_tz_check_n_skip_implicit_tables():
    We should set SELECT_ACL for implictly opened tables to be able to
    bypass privilege checking in check_grant().