Pick up QT_LOGGING_RULES also for bootstrapped tools

Pick up logging rules set by QT_LOGGING_CONF, QT_LOGGING_RULES,
and qtlogging.ini file also for bootstrapped tools. This helps e.g.
in the case of winrtrunner, which uses categorized logging.

Change-Id: I47d392137e17a59cb57b5c0226f282b0ccf29961
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@theqtcompany.com>