Update allocator implementations to C++17 standard (#1265)
Update allocator implementations to C++17 standard (#1265)


halfflat/nestmc-proto,eth-cscs/nestmc-proto,eth-cscs/nestmc-proto,halfflat/nestmc-proto,halfflat/arbor,halfflat/arbor,halfflat/nestmc-proto,eth-cscs/nestmc-proto,halfflat/arbor,halfflat/arbor,halfflat/arbor