new cpuset format on the command-line

[bgoglin]

There was some discussion recently about a new cpuset output format in hwloc-calc to be compatible with some systemd tools (busctl for manipulating cgroups). We have taskset support in hwloc-calc/bind/distrib. There are also taskset and cpulist variants to bitmap_sscanf() and printf() API. Starting with 2.11, --taskset is replaced with --cpuset-output-format which also accepts "list".

A new format for systemd wouldn't be added to the API, only to CLI tools, likely even only for output.