Allow builds with glibc 2.20.
Based on a patch by Peter Hutterer <peter.hutterer@who-t.net>.
See <https://raw.githubusercontent.com/openembedded/oe-core/master/meta/recipes-graphics/xorg-driver/xf86-input-synaptics/always_include_xorg_server.h.patch>.

--- xf86-video-intel-2.21.15/src/intel_device.c.~1~	2013-08-09 16:58:48.000000000 -0400
+++ xf86-video-intel-2.21.15/src/intel_device.c	2014-12-18 00:03:54.700759577 -0500
@@ -33,6 +33,8 @@
 
 #include <sys/ioctl.h>
 
+#include <xorg-server.h>
+
 #include <pciaccess.h>
 #include <xf86.h>
 #include <xf86drm.h>
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<tr><td><span title='2020-05-11 23:30:54 +0200'>2020-05-11</span></td><td><a href='/guix/commit/tests/guix-package-aliases.sh?id=647c57207a36435fe4da20a1c8f4cd4bf7234d5b'>tests: Test 'guix show' with multiple packages.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-09-21 16:48:36 +0200'>2019-09-21</span></td><td><a href='/guix/commit/tests/guix-package-aliases.sh?id=660dbe65641851aa99b810e4ae065a5f72dc37d0'>guix package: '--show' ignores deprecated packages.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-09-21 16:48:36 +0200'>2019-09-21</span></td><td><a href='/guix/commit/tests/guix-package-aliases.sh?id=aeb51370da7c854e8167066df9b138e15d7363e6'>guix package: Add 'guix show' alias.</a><span class='msg-avail'>...</span></td><td>zimoun</td></tr>
<tr><td><span title='2019-04-29 12:19:24 +0200'>2019-04-29</span></td><td><a href='/guix/commit/tests/guix-package-aliases.sh?id=da56f10971e0b6f32969b10e38ed043b2c99bb82'>guix package: Add 'guix search' alias.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-04-29 10:13:44 +0200'>2019-04-29</span></td><td><a href='/guix/commit/tests/guix-package-aliases.sh?id=d824cfbabeb0780c9ea7a6dab02c47b6a4d029c6'>guix package: Add 'install', 'remove', and 'upgrade' aliases.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>