merge security fixes from xorg-server 21.1.9 into xorg-server 10.

Fixes CVE-2023-5367 and CVE-2023-5380.

Add compatibility to xorg-server-120
- Convert display modes arguments to const.
- Provive bswap* in misc.h
- Provide missing cursor function

port to xorg-server 1.10:

apply
https://cgit.freedesktop.org/xorg/xserver/commit/?id=957e8db38f27932d353e86e9aa69cf16778b18f1

--
Use arc4random_buf(3) if available to generate cookies.

Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Matthieu Herrb <matthieu@herrb.eu>
--

port to xorg-server 1.10:

--
Log Message:
apply

https://cgit.freedesktop.org/xorg/xserver/commit/?id=d7ac755f0b618eb1259d93c8a16ec6e39a18627c

Use timingsafe_memcmp() to compare MIT-MAGIC-COOKIES CVE-2017-2624
Provide the function definition for systems that don't have it.

Signed-off-by: Matthieu Herrb <matthieu@herrb.eu>
Reviewed-by: Alan Coopersmith <alan.coopersmith@oracle.com>

and
https://cgit.freedesktop.org/xorg/xserver/commit/?id=5c44169caed811e59a65ba346de1cadb46d266ec

os: Squash missing declaration warning for timingsafe_memcmp
timingsafe_memcmp.c:21:1: warning: no previous prototype for `timingsafe_memcmp' [-Wmissing-prototypes]
timingsafe_memcmp(const void *b1, const void *b2, size_t len)

Signed-off-by: Adam Jackson <ajax@redhat.com>
--

initial import of existing netbsd xorg-server 1.10 sources in the
xorg-server.old subdir.