Nonblocking backend may perform dynamic allocations

[anyzelman]

E.g., in nonblocking/blas1.hpp:553 . It should instead rely on the internal global buffer for such things, as otherwise it clashes with performance semantics (which typically prefer no system calls may be made, including allocations) while the current solution is also not using NUMA-aware allocation (which the global buffer does use).

[anyzelman]

Prioritising higher as the use in nonblocking/coordinates.hpp seems to indicate false sharing is possible

[anyzelman]

Prioritising higher as the use in nonblocking/coordinates.hpp seems to indicate false sharing is possible

more precisely, false sharing on local_prefix_sum in the function prefixSumComputation()