C++14's initializer_list::size() doesn't work in static_assert
C++14's initializer_list::size() doesn't work in static_assert

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

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