[BUGFIX] Use of undefined constant E_DEBUG

Global function debug() initializes its 6th argument
to constant E_DEBUG which does not exist and then defaults
to string 'E_DEBUG'. This raises a PHP 7.2 warning.
Relevant for v8 & v7 only, this argument has been removed
in master already.
Fix by defaulting to string 'E_DEBUG' in method signature.

Change-Id: If04c9e55bb810980b19b924496680ea1758e4b24
Resolves: #83200
Related: #82640
Releases: 8.7, 7.6
Reviewed-on: https://review.typo3.org/54915


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>