MDEV-5419 no audit events for warnings converted to errors in the strict mode.

Plugins get error notifications only when my_message_sql() is called.
        But errors are launched with THD::raise_condition() calls in other
        places. These are push_warning(), implementations of SIGNAL and
        RESIGNAL commands.
        So it makes sence to notify plugins there in THD::raise_condition().

sql/sql_class.cc

@@ -1145,6 +1145,7 @@ MYSQL_ERROR* THD::raise_condition(uint sql_errno,
     got_warning= 1;
     break;
   case MYSQL_ERROR::WARN_LEVEL_ERROR:
+    mysql_audit_general(this, MYSQL_AUDIT_GENERAL_ERROR, sql_errno, msg);
     break;
   default:
     DBUG_ASSERT(FALSE);