xorg: bump X.org server version to 1.5.3

This version contains a fix to allow the compilation of the Xvesa
server against recent versions of the kernel headers (fix
http://cgit.freedesktop.org/xorg/xserver/commit/?h=server-1.5-branch&id=992a7168f0db5733fe4a6cbd2f40c6b1f2a150e0)

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/x11r7/xserver_xorg-server/xserver_xorg-server.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-XSERVER_XORG_SERVER_VERSION = 1.5.2
+XSERVER_XORG_SERVER_VERSION = 1.5.3
 XSERVER_XORG_SERVER_SOURCE = xorg-server-$(XSERVER_XORG_SERVER_VERSION).tar.bz2
 XSERVER_XORG_SERVER_SITE = http://xorg.freedesktop.org/releases/individual/xserver
 XSERVER_XORG_SERVER_AUTORECONF = NO