SSE: fix casts_VC_EXTRA_TYPES_sse
SSE: fix casts_VC_EXTRA_TYPES_sse

Several multi-arg casts from Scalar to SSE were missing. While at it I
reorganized the code into declarations and definitions, similar to the
AVX simd_cast file.

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

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