MDEV-15719 ALTER TABLE…ALGORITHM=INPLACE is unnecessarily refused due to innodb_force_recovery

ha_innobase::check_if_supported_inplace_alter(): Only check for
high_level_read_only. Do not unnecessarily refuse
ALTER TABLE...ALGORITHM=INPLACE if innodb_force_recovery was
specified as 1, 2, or 3.

innobase_start_or_create_for_mysql(): Block all writes from SQL
if the system tablespace was initialized with 'newraw'.

storage/innobase/handler/handler0alter.cc

@@ -580,11 +580,8 @@ ha_innobase::check_if_supported_inplace_alter(
 		DBUG_RETURN(HA_ALTER_INPLACE_NOT_SUPPORTED);
 	}
 
-	if (high_level_read_only
-	    || srv_sys_space.created_new_raw()
-	    || srv_force_recovery) {
-		ha_alter_info->unsupported_reason = (srv_force_recovery)?
-			"Operation not allowed when innodb_forced_recovery > 0." :
+	if (high_level_read_only) {
+		ha_alter_info->unsupported_reason =
 			innobase_get_err_msg(ER_READ_ONLY_MODE);
 
 		DBUG_RETURN(HA_ALTER_INPLACE_NOT_SUPPORTED);

storage/innobase/srv/srv0start.cc

@@ -1504,7 +1504,8 @@ innobase_start_or_create_for_mysql()
 	}
 
 	high_level_read_only = srv_read_only_mode
-		|| srv_force_recovery > SRV_FORCE_NO_TRX_UNDO;
+		|| srv_force_recovery > SRV_FORCE_NO_TRX_UNDO
+		|| srv_sys_space.created_new_raw();
 
 	/* Reset the start state. */
 	srv_start_state = SRV_START_STATE_NONE;