[BUGFIX] Fix declaration of injectView in install tool

When using PHP7 declarations of sub classes have to
be compatible to their parent declarations.

As the install tool has been completely refactored in
newer TYPO3 version this patch implements only a
workaround to prevent the PHP warning.

Change-Id: I4128b3aef30a3a1bb9de6188509db1cdf4314b02
Resolves: #77203
Releases: 7.6
Reviewed-on: https://review.typo3.org/54417


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