Bug#1038386: get_nprocs_conf value higher than is present CPUs.

[Junichi Uekawa <dancer@netfort.gr.jp>]

Package: libc6
Version: 2.36-9

Documentation tells me that 
 
  sysconf(_SC_NPROCESSORS_CONF)
  get_nprocs_conf()

gives me the upper bound of CPUs and 

  sysconf(_SC_NPROCESSORS_ONLN)
  get_nprocs()

gives the currently online CPUs.

get_nprocs_conf seems to return "possible" value, and it seems like
the value is 32 on my system.  However from reading
Documentation/ABI/testing/sysfs-devices-system-cpu "present" might be
more suited instead of "possible".

(the value used to be 12 on bullseye kernel, and bookworm kernel
started reporting 32 for possible, which maybe possible but not very
useful as only 12 is present on my system.)



I think one of the following could be useful

- use "present" instead of possible for get_nprocs_conf
- update get_nprocs_conf to document that it's a theoretical value and not the number of present cpus.
- introduce another API for the present CPUs that may or may not be online.