In index.php AND typo3/sysext/cms/tslib/index_ts.php
(which will be included in index.php) the constant
PATH_tslib is defined.

The definition in typo3/sysext/cms/tslib/index_ts.php
is obsolete, because this will be checked via if(!defined(...)).

In index.php, if PATH_tslib is empty the script will die immediately.
After that check, PATH_tslib will be used to include index_ts.php

See also #35003 and #35017

Change-Id: I6b86c3bdb071af06b2c64b8cbbc977e9387408c8
Fixes: #35019
Releases: 6.0, 4.7
Reviewed-on: http://review.typo3.org/9754
Reviewed-by: Andy Grunwald
Tested-by: Andy Grunwald
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn