The principle remains the same, but instead of having a single process
and ignoring extra ones, now we set the affinity masks for the respective
threads of all groups.

The doc was updated with a few extra examples.

The man page indicates that CPU_AND() and CPU_ASSIGN() take a variable,
not a const on the source, even though it doesn't make much sense. But
with older libcs, this triggers a build warning:

  src/cpuset.c: In function 'ha_cpuset_and':
  src/cpuset.c:53: warning: initialization discards qualifiers from pointer target type
  src/cpuset.c: In function 'ha_cpuset_assign':
  src/cpuset.c:101: warning: initialization discards qualifiers from pointer target type

Better stick stricter to the documented API as this is really harmless
here. There's no need to backport it (unless build issues are reported,
which is quite unlikely).

"f(void)" is the correct and preferred form for a function taking no
argument, while some places use the older "f()". These were reported
by clang's -Wmissing-prototypes, for example:

  src/cpuset.c:111:5: warning: no previous prototype for function 'ha_cpuset_size' [-Wmissing-prototypes]
  int ha_cpuset_size()
  include/haproxy/cpuset.h:42:5: note: this declaration is not a prototype; add 'void' to make it a prototype for a zero-parameter function
  int ha_cpuset_size();
      ^
                     void

This aggregate patch fixes this for the following functions:

   ha_backtrace_to_stderr(), ha_cpuset_size(), ha_panic(), ha_random64(),
   ha_thread_dump_all_to_trash(), get_exec_path(), check_config_validity(),
   mworker_child_nb(), mworker_cli_proxy_(create|stop)(),
   mworker_cleantasks(), mworker_cleanlisteners(), mworker_ext_launch_all(),
   mworker_reload(), mworker_(env|proc_list)_to_(proc_list|env)(),
   mworker_(un|)block_signals(), proxy_adjust_all_maxconn(),
   proxy_destroy_all_defaults(), get_tainted(),
   pool_total_(allocated|used)(), thread_isolate(_full|)(),
   thread(_sync|)_release(), thread_harmless_till_end(),
   thread_cpu_mask_forced(), dequeue_all_listeners(), next_timer_expiry(),
   wake_expired_tasks(), process_runnable_tasks(), init_acl(),
   init_buffer(), (de|)init_log_buffers(), (de|)init_pollers(),
   fork_poller(), pool_destroy_all(), pool_evict_from_local_caches(),
   pool_total_failures(), dump_pools_to_trash(), cfg_run_diagnostics(),
   tv_init_(process|thread)_date(), __signal_process_queue(),
   deinit_signals(), haproxy_unblock_signals()

Move cpu_map structure outside of the global struct to a global
variable defined in cpuset.c compilation unit. This allows to reorganize
the includes without having to define _GNU_SOURCE everywhere for the
support of the cpu_set_t.

This fixes the compilation with musl libc, most notably used for the
alpine based docker image.

This fixes the github issue #1235.

No need to backport as this feature is new in the current
2.4-dev.

This is 22nd iteration of typo fixes

This module can be used to manipulate a cpu sets in a platform agnostic
way. Use the type cpu_set_t/cpuset_t if available on the platform, or
fallback to unsigned long, which limits de facto the maximum cpu index
to LONGBITS.