unittest: use const-ref to get rid of ABI note
unittest: use const-ref to get rid of ABI note

GCC notes that parameter passing of overaligned types has changed. I
don't care for passing these parameters here, actually. It's just a
dispatch method, so use const-ref instead to silence the "note".

Signed-off-by: Matthias Kretz <372ea4eca737a13cd010ee806d4ce7b98ee71550@kde.org>

VcDevel/Vc,chr-engwer/Vc,chr-engwer/Vc,VcDevel/Vc,chr-engwer/Vc,VcDevel/Vc,VcDevel/Vc