xorg-server: security update to RC1 of 1.16.3

Close #5292. There are almost no other changes since 1.16.2
than fixing that CVE-2014-8092. See also:
http://www.x.org/wiki/Development/Security/Advisory-2014-12-09/

(cherry picked from commit 84d6debf46a22cf08710e094dce0bfc652f729d3)