Replace uses of g_test_add_data_func() for QTest test cases.

It is still valid to use it for any non-QTest test cases,
which are not run for multiple target binaries.
Suggested-by: NJohn Snow <jsnow@redhat.com>
Reviewed-by: NJohn Snow <jsnow@redhat.com>
Signed-off-by: NAndreas Färber <afaerber@suse.de>