AVX: new helper macro to get rid of the name clashes

Signed-off-by: Matthias Kretz <kretz@kde.org>
AVX: the alignr forward is already implemented above

Signed-off-by: Matthias Kretz <kretz@kde.org>
math test: improve frexp test COMPARE usage

Signed-off-by: Matthias Kretz <kretz@kde.org>
simdarray test: () for broadcast, {} is init list

Signed-off-by: Matthias Kretz <kretz@kde.org>
AVX: define fewer functions with _mm prefix

Leading underscores are best left for compilers and the system. As I
declare my functions in the Vc namespace I don't need this prefix.

This also allows me to do more overloading on the function parameters,
thus making it easier to write the same code for 128- and 256-bit
vectors.

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