Bug#17733 Flushing logs causes daily server crash

Server crashes if a flush commmand is issued and binlog is closed.
- added check to prevent binlog access when binlog file isn't opened.

mysql-test/r/flush2.result

+flush logs;
+set global expire_logs_days = 3;
+show variables like 'log%';
+Variable_name	Value
+log	ON
+log_bin	OFF
+log_bin_trust_function_creators	ON
+log_error	
+log_queries_not_using_indexes	OFF
+log_slave_updates	OFF
+log_slow_queries	OFF
+log_warnings	1
+flush logs;
+show variables like 'log%';
+Variable_name	Value
+log	ON
+log_bin	OFF
+log_bin_trust_function_creators	ON
+log_error	
+log_queries_not_using_indexes	OFF
+log_slave_updates	OFF
+log_slow_queries	OFF
+log_warnings	1
+set global expire_logs_days = 0;

mysql-test/t/flush2-master.opt

+--disable-log-bin

mysql-test/t/flush2.test

+#
+# Bug#17733 Flushing logs causes daily server crash
+#
+flush logs;
+set global expire_logs_days = 3;
+show variables like 'log%';
+flush logs;
+show variables like 'log%';
+set global expire_logs_days = 0;

sql/sql_parse.cc

@@ -4008,8 +4008,9 @@ mysql_execute_command(THD *thd)
   case SQLCOM_FLUSH:
   {
     bool write_to_binlog;
-    if (check_global_access(thd,RELOAD_ACL) || check_db_used(thd, all_tables))
+    if (check_global_access(thd,RELOAD_ACL))
       goto error;
+
     /*
       reload_acl_and_cache() will tell us if we are allowed to write to the
       binlog or not.
@@ -4031,6 +4032,7 @@ mysql_execute_command(THD *thd)
       }
       send_ok(thd);
     } 
+    
     break;
   }
   case SQLCOM_KILL:
@@ -6696,7 +6698,10 @@ bool reload_acl_and_cache(THD *thd, ulong options, TABLE_LIST *tables,
     tmp_write_to_binlog= 0;
     mysql_log.new_file(1);
     mysql_slow_log.new_file(1);
+    if( mysql_bin_log.is_open() )
+    {
       mysql_bin_log.rotate_and_purge(RP_FORCE_ROTATE);
+    }
 #ifdef HAVE_REPLICATION
     pthread_mutex_lock(&LOCK_active_mi);
     rotate_relay_log(active_mi);