Changed some startup warnings to notes

- Changed 'WARNING' of type "You need to use --log-bin to make ... work"
  to 'Note'
- Only print startup Notes if log_warnings >= 4

mysql-test/suite/binlog/t/binlog_expire_warnings.opt

+--log-warnings=4

sql/mysqld.cc

@@ -5004,11 +5004,11 @@ static int init_server_components()
   /* need to configure logging before initializing storage engines */
   if (!opt_bin_log_used && !WSREP_ON)
   {
-    if (opt_log_slave_updates && (global_system_variables.log_warnings > 1))
-      sql_print_warning("You need to use --log-bin to make "
+    if (opt_log_slave_updates && (global_system_variables.log_warnings >= 4))
+      sql_print_information("You need to use --log-bin to make "
                             "--log-slave-updates work.");
-    if (binlog_format_used && (global_system_variables.log_warnings > 1))
-      sql_print_warning("You need to use --log-bin to make "
+    if (binlog_format_used && (global_system_variables.log_warnings >= 4))
+      sql_print_information("You need to use --log-bin to make "
                             "--binlog-format work.");
   }
 
@@ -5497,8 +5497,8 @@ static int init_server_components()
   }
   else
   {
-    if (binlog_expire_logs_seconds && (global_system_variables.log_warnings > 1))
-      sql_print_warning("You need to use --log-bin to make --expire-logs-days "
+    if (binlog_expire_logs_seconds && (global_system_variables.log_warnings >= 4))
+      sql_print_information("You need to use --log-bin to make --expire-logs-days "
                              "or --binlog-expire-logs-seconds work.");
   }
 #endif