bits/sched.h has logic to expose only an impl-namespace variant of
struct sched_param (i.e. struct __sched_param), but nothing uses it,
and the only header that includes bits/sched.h is sched.h. The
__need_schedparam logic can therefore be removed.
bits/sched.h also has a great deal of code relating to cpu_set_t
objects that was *almost* the same between the two versions of
bits/sched.h in the tree; a little spelunking indicated that this is
because some bug fixes got applied to the Linux-specific bits/sched.h
but not the generic one. Introduce a new header, bits/cpu-set.h,
containing the version of that code with the bugfixes, have sched.h
include it directly, and delete all of the code from both versions of
bits/sched.h.
Also remove the unnecessary name mangling in the definition of struct
sched_param -- POSIX specifies a field 'sched_priority', so there is
no reason to define it as '__sched_priority' and then paper over that
with a macro. (Just in case someone was using the internal name,
'sched_priority' remains a macro defined to expand to itself, and
'__sched_priority' now expands to 'sched_priority'.)
Finally, as long as I'm touching these files anyway, merge new
constants from linux/sched.h into the Linux bits/sched.h.
* bits/sched.h: Remove __need_schedparam logic and replace with a
normal multiple-include guard. Change field name in struct
sched_param from __sched_priority to sched_priority. Delete
everything under #ifndef __cpu_set_t_defined.
* sysdeps/unix/sysv/linux/bits/sched.h: Likewise. Also sync with
kernel sched.h, adding SCHED_ISO and SCHED_DEADLINE constants.
* posix/sched.h: Include bits/cpu-set.h as well as bits/sched.h.
For compatibility, #define sched_priority to itself, and #define
__sched_priority as sched_priority.
* posix/bits/cpu-set.h: New file containing, verbatim, the code
that was under #ifndef __cpu_set_t_defined in
sysdeps/unix/sysv/linux/bits/sched.h.
* include/bits/cpu-set.h: New wrapper.
* posix/Makefile: Install bits/cpu-set.h.
