[TASK] Always display errors when running the tests

With some default php.ini files (e.g., the file shipped with MAMP PRO),
display_errors is set to "off", and the memory limit is rather low.

As the bootstraps for the unit and functional tests do not read the
current installation's settings, the default values from the php.ini
are used. This can cause the tests to fail at some point due to
insufficient memory, but without any visible messages.

This change makes sure that PHP errors always are output when running
the unit or functional tests using the Core bootstrap files.

Resolves: #64659
Releases: master, 6.2
Change-Id: I28773515b354811a42f0ce262e950603218927b6
Reviewed-on: http://review.typo3.org/36462


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>