otherwise, enabled, if there exists a vectorizable type T and a
value N in the range [1, 64] such that Bytes is equal
to sizeof(T) and Abi is deduce-abi-t<T,
N>,
otherwise, it is implementation-defined if such a specialization is enabled.
If basic_simd_mask<Bytes, Abi> is disabled, the specialization has a
deleted default constructor, deleted destructor, deleted copy constructor, and
deleted copy assignment.
In addition only the value_type and abi_type members are
present.
If basic_simd_mask<Bytes, Abi> is enabled,
basic_simd_mask<Bytes, Abi> is trivially copyable.
Recommended practice: Implementations should support explicit conversions between
specializations of basic_simd_mask and appropriate implementation-defined types.