MDEV-13499: Backing up table that "doesn't exist in engine" cause crash in mariabackup when using encryption

Problem was that there is intentional crah when .ibd file does
not found. In mariabackup case we should avoid this crash.

Author: Jan Lindström

mysql-test/suite/mariabackup/missing_ibd.result

@@ -0,0 +1,6 @@
+create table t1(c1 int) engine=InnoDB;
+INSERT INTO t1 VALUES(1);
+# xtrabackup backup
+select * from t1;
+ERROR 42S02: Table 'test.t1' doesn't exist in engine
+drop table t1;

mysql-test/suite/mariabackup/missing_ibd.test

@@ -0,0 +1,27 @@
+--source include/have_innodb.inc
+
+#
+# MDEV-13499: Backing up table that "doesn't exist in engine" cause crash in mariabackup when using encryption
+#
+create table t1(c1 int) engine=InnoDB;
+INSERT INTO t1 VALUES(1);
+let MYSQLD_DATADIR=`select @@datadir`;
+
+--source include/shutdown_mysqld.inc
+
+--remove_file $MYSQLD_DATADIR/test/t1.ibd
+
+--source include/start_mysqld.inc
+
+echo # xtrabackup backup;
+let $targetdir=$MYSQLTEST_VARDIR/tmp/backup;
+--disable_result_log
+exec  $XTRABACKUP --defaults-file=$MYSQLTEST_VARDIR/my.cnf --backup --target-dir=$targetdir;
+--enable_result_log
+
+rmdir $targetdir;
+
+--error ER_NO_SUCH_TABLE_IN_ENGINE
+select * from t1;
+drop table t1;
+

storage/xtradb/fil/fil0fil.cc

@@ -1,7 +1,7 @@
 /*****************************************************************************
 
 Copyright (c) 1995, 2017, Oracle and/or its affiliates. All Rights Reserved.
-Copyright (c) 2014, 2017, MariaDB Corporation.
+Copyright (c) 2014, 2018, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -4967,6 +4967,11 @@ fil_load_single_table_tablespace(
 			return;
 		}
 
+		/* In mariabackup lets not crash. */
+		if (IS_XTRABACKUP()) {
+			return;
+		}
+
 		abort();
 	}