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>