simd_cast: offset==0 from SSE may only cast to SSE and Scalar
simd_cast: offset==0 from SSE may only cast to SSE and Scalar

It doesn't know about AVX yet, therefore the function should not
participate in overloading when the Return type is an AVX Vector/Mask

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

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