So that it won't just return "Helvetica" that may not exist in
target system. Providing it seems to fix QTBUG-21833 as well,
thus we can remove the QEXPECT_FAIL statement in qlistview test.
'_' appears to reach the minimum right bearing in some fonts.
Task-number: QTBUG-21833
Change-Id: I2340af6ee736083ec4f6575e469840ebec4e545e
Reviewed-by: Jiang Jiang <jiang.jiang@nokia.com>