cmake: don't warn about missing MIC SDK

a status message is enough. it's perfectly fine to work on a non-MIC
development environment.

Signed-off-by: Matthias Kretz <kretz@kde.org>
NEON: stub vector.h from AVX

Signed-off-by: Matthias Kretz <kretz@kde.org>
NEON: more boilerplate interface code

Signed-off-by: Matthias Kretz <kretz@kde.org>
NEON: include logic for NEON

Signed-off-by: Matthias Kretz <kretz@kde.org>
NEON: more neon impl stub files

Signed-off-by: Matthias Kretz <kretz@kde.org>
NEON: clean up Vector<T> class for NEON

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