Update.
* misc/sys/cdefs.h: Define __restrict_arr.
* include/sys/time.h: Add restrict where required by AGd4.
* inet/arpa/inet.h: Likewise.
* io/sys/stat.h: Likewise.
* io/sys/statvfs.h: Likewise.
* misc/search.h: Likewise.
* misc/sys/select.h: Likewise.
* posix/glob.h: Likewise.
* posix/regex.h: Likewise.
* posix/spawn.h: Likewise.
* posix/unistd.h: Likewise.
* rt/aio.h: Likewise.
* signal/signal.h: Likewise.
* socket/sys/socket.h: Likewise.
* stdlib/ucontext.h: Likewise.
* streams/stropts.h: Likewise.
* string/string.h: Likewise.
* time/time.h: Likewise.
* time/sys/time.h: Likewise.
* posix/spawn.h: Add declarations for posix_spawnattr_getscheparam
and posix_spawnattr_setscheparam.
* libio/stdio.h: Make cuserid prototype again available for all
XPG versions.