MDEV-12215: main.repair_symlink-5543 fails in buildbot

If openat is present on the system and it tries to open a symlink with
O_NOFOLLOW, we get errno 40.

If openat is not present on the system, we use the alternative open call, with
slightly different logic. IF the symlink doesn't point to a valid file,
we get errno 20. This test uses an invalid symlink on the table t1.MYD.

mysql-test/r/repair_symlink-5543.result

 create table t1 (a int) engine=myisam data directory='MYSQL_TMP_DIR';
 insert t1 values (1);
+# Some systems fail with errcode 40, when doing openat, while others
+# don't have openat and fail with errcode 20.
 repair table t1;
 Table	Op	Msg_type	Msg_text
-test.t1	repair	error	40 for record at pos 0
-test.t1	repair	Error	File 'MYSQL_TMP_DIR/t1.MYD' not found (Errcode: 40 "Too many levels of symbolic links")
+test.t1	repair	error	20 for record at pos 0
+test.t1	repair	Error	File 'MYSQL_TMP_DIR/t1.MYD' not found (Errcode: 20 "<errmsg>")
 test.t1	repair	status	Operation failed
 drop table t1;
 create table t2 (a int) engine=aria data directory='MYSQL_TMP_DIR';

mysql-test/t/repair_symlink-5543.test

@@ -9,7 +9,9 @@
 eval create table t1 (a int) engine=myisam data directory='$MYSQL_TMP_DIR';
 insert t1 values (1);
 --system ln -s $MYSQL_TMP_DIR/foobar5543 $MYSQL_TMP_DIR/t1.TMD
---replace_regex / '.*\/t1/ 'MYSQL_TMP_DIR\/t1/
+--echo # Some systems fail with errcode 40, when doing openat, while others
+--echo # don't have openat and fail with errcode 20.
+--replace_regex / '.*\/t1/ 'MYSQL_TMP_DIR\/t1/ /40/20/ /".*"/"<errmsg>"/
 repair table t1;
 drop table t1;