[TASK] Ignore cm1/index.php in scrutinizer php analyzer

This has to be done as scrutinizer crashes when analyzing
the file cm1/index.php.

Releases: 2.0.0
Change-Id: Ie96a98715ce15798ea7f1148ab47333cfd36a66d
Reviewed-on: https://review.typo3.org/31429
Reviewed-by: Wouter Wolters
Reviewed-by: Alexander Schnitzler
Tested-by: Alexander Schnitzler