Allow builds with libc 2.20.
Patch from <https://raw.githubusercontent.com/openembedded/oe-core/master/meta/recipes-graphics/xorg-driver/xf86-input-synaptics/always_include_xorg_server.h.patch>.

From 96e60a4ea242d2decf109835981ae186cc36f642 Mon Sep 17 00:00:00 2001
From: Peter Hutterer <peter.hutterer@who-t.net>
Date: Fri, 29 Aug 2014 07:57:41 +1000
Subject: Include xorg-server.h to fix build errors on newest glibc

In file included from /usr/include/string.h:634:0,
                 from /usr/include/xorg/os.h:53,
                 from /usr/include/xorg/misc.h:115,
                 from /usr/include/xorg/xf86str.h:37,
                 from /usr/include/xorg/xf86Xinput.h:54,
                 from synproto.h:36,
                 from synproto.c:24:
/usr/include/xorg/os.h:579:1: error: expected identifier or '(' before '__extension__'
 strndup(const char *str, size_t n);

See http://lists.freedesktop.org/archives/xorg-devel/2014-July/043070.html

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

Status: Backport

Index: xf86-input-synaptics-1.8.0/src/eventcomm.h
===================================================================
--- xf86-input-synaptics-1.8.0.orig/src/eventcomm.h	2014-08-28 18:40:28.628070587 -0700
+++ xf86-input-synaptics-1.8.0/src/eventcomm.h	2014-08-28 18:40:28.620070587 -0700
@@ -27,6 +27,8 @@
 #ifndef _EVENTCOMM_H_
 #define _EVENTCOMM_H_
 
+#include <xorg-server.h>
+
 #include <linux/input.h>
 #include <linux/version.h>
 #include <xf86Xinput.h>
Index: xf86-input-synaptics-1.8.0/src/ps2comm.h
===================================================================
--- xf86-input-synaptics-1.8.0.orig/src/ps2comm.h	2014-08-28 18:40:28.628070587 -0700
+++ xf86-input-synaptics-1.8.0/src/ps2comm.h	2014-08-28 18:40:28.620070587 -0700
@@ -22,6 +22,8 @@
 #ifndef _PS2COMM_H_
 #define _PS2COMM_H_
 
+#include <xorg-server.h>
+
 #include <unistd.h>
 #include <sys/ioctl.h>
 #include "xf86_OSproc.h"
Index: xf86-input-synaptics-1.8.0/src/synproto.h
===================================================================
--- xf86-input-synaptics-1.8.0.orig/src/synproto.h	2014-08-28 18:40:28.628070587 -0700
+++ xf86-input-synaptics-1.8.0/src/synproto.h	2014-08-28 18:40:28.624070587 -0700
@@ -31,6 +31,8 @@
 #include "config.h"
 #endif
 
+#include <xorg-server.h>
+
 #include <unistd.h>
 #include <sys/ioctl.h>
 #include <xf86Xinput.h>