In particular:
Add timerfd constants and functions, from sys/timerfd.h.
Add EFD_SEMAPHORE and group all EFD_ constants together.
Add sigtimedwait function, from signal.h.
Add missing fallocate constants and functions, from linux/falloc.h and fcntl.h.
Add xattr functions, from sys/xattr.h.
Add SCHED_ and SEEK_ constants, from linux/sched.h and bits/seek_constants.h.
Add rlimit functions, from sys/resource.h.
Add RENAME_ constants, from stdio.h.
Add ino64_t type, from sys/types.h.

This commit defines ETIMEDOUT, SIGSTKSZ, MINSIGSTKSZ

SmartOS is a downstream distribution of illumos, and carries a number of
additional patches that are not commonly available in other illumos
distributions.  They are also not found in Oracle Solaris.  With these
removed, the libc tests pass on a stock illumos system running
OpenIndiana.

This patchs adds missing flag values for getnameinfo()
on FreeBSD, the following flags have been added from
the FreeBSD tree.

 /*
  * Flag values for getnameinfo()
  */
 #define	NI_NOFQDN	0x00000001
 #define	NI_NUMERICHOST	0x00000002
 #define	NI_NAMEREQD	0x00000004
 #define	NI_NUMERICSERV	0x00000008
 #define	NI_DGRAM	0x00000010
 #define	NI_NUMERICSCOPE	0x00000020

Signed-off-by: Valdemar Erk <valdemar@erk.io>

Reorganized some constants as well so they're grouped a bit better.

Signed-off-by: Robert Collins <robertc@robertcollins.net>

Co-Authored-By: Yuki Okushi <huyuumi.dev@gmail.com>

Like on NetBSD, but without a pid field in the struct.

It is present on both FreeBSD and DragonFly

revenge of #598