package/x11r7/xserver_xorg-server: bump to version 1.17.2

Removed patches committed upstream:
http://cgit.freedesktop.org/xorg/xserver/commit/os/backtrace.c?h=server-1.17-branch&id=8b7e1f362bf6940eb863fd02395bf8155d10604b
http://cgit.freedesktop.org/xorg/xserver/commit/hw/xfree86/sdksyms.sh?h=server-1.17-branch&id=7a45d1684f626f3045305328c3aab85eed0673ea



Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>