stlcontainer: convert to new unittest interface

Signed-off-by: Matthias Kretz <kretz@kde.org>
global: VC_CXX14 macro

VC_CXX14 is defined if __cplusplus says C++14 is supported

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

like std::for_each, but reads the data as Vector<T> and requires generic
lambdas to feed it to the function as scalars and vectors.

Signed-off-by: Matthias Kretz <kretz@kde.org>
namespaces: add comment on closing brace

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