vbslq_f64 and vandq_u64 both require uint64x2_t types as mask arguments,
and the Neon intrinsics do not allow for implicit conversion.
Fixes build errors with current GCC 11.2.1:
/home/abuild/rpmbuild/BUILD/netgen-6.2.2105/libsrc/core/simd_arm64.hpp:171:29: error: cannot convert '__Int64x2_t' to 'uint64x2_t'
171 | return vandq_u64 (a.Data(), b.Data());