Fix test compilation with exa.h in configure when using glibc 2.20.
Inspired by 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-mach64-6.9.4/configure.~1~	2012-12-20 01:16:10.000000000 -0500
+++ xf86-video-mach64-6.9.4/configure	2014-12-19 02:48:18.040097554 -0500
@@ -18370,7 +18370,9 @@
 
         SAVE_CPPFLAGS="$CPPFLAGS"
         CPPFLAGS="$CPPFLAGS $XORG_CFLAGS"
-        ac_fn_c_check_header_mongrel "$LINENO" "exa.h" "ac_cv_header_exa_h" "$ac_includes_default"
+        ac_fn_c_check_header_mongrel "$LINENO" "exa.h" "ac_cv_header_exa_h" "$ac_includes_default
+#include <xorg-server.h>
+"
 if test "x$ac_cv_header_exa_h" = xyes; then :
   have_exa_h="yes"
 else
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<div class='path'>path: <a href='/guix/log/?id=23a575f97cab5b86a72391dd4ab3b937cd70d8a9&amp;showmsg=1'>root</a>/<a href='/guix/log/nix?id=23a575f97cab5b86a72391dd4ab3b937cd70d8a9&amp;showmsg=1'>nix</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/nix?id=23a575f97cab5b86a72391dd4ab3b937cd70d8a9'>Collapse</a>)</th><th class='left'>Author</th></tr>
<tr class='logheader'><td><span title='2023-01-09 17:40:54 +0100'>2023-01-09</span></td><td class='logsubject'><a href='/guix/commit/nix?id=407175a1d0e29f45639e7f28a531b3981cd20085'>daemon: Improve error message for wrong hash sizes.</a></td><td>Ludovic Courtès</td></tr>
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* nix/libutil/hash.cc (parseHash): Show the hash algorithm name and
expected size in the error message.
* tests/derivations.scm ("fixed-output derivation, invalid hash size"):
New test.


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<tr class='logheader'><td><span title='2022-12-18 01:16:47 +0100'>2022-12-18</span></td><td class='logsubject'><a href='/guix/commit/nix?id=2d4d26769d6a3be1b21302b0bb2bd099fd55ccf8'>daemon: Make "opening file" error messages distinguishable.</a></td><td>Ludovic Courtès</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* nix/libstore/build.cc (DerivationGoal::openLogFile): Customize
"opening file" error message.
* nix/libutil/hash.cc (hashFile): Likewise.
* nix/libutil/util.cc (readFile, writeFile): Likewise.


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<tr class='logheader'><td><span title='2022-10-17 09:37:27 +0200'>2022-10-17</span></td><td class='logsubject'><a href='/guix/commit/nix?id=eec920ba93ecb086366576e31b785962fbaf81c2'>Revert "nix: Guard against removing temporary roots of living processes."</a></td><td>Ludovic Courtès</td></tr>
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This reverts commit bb0beaecdee1a2315a1269b1746d238c8ab0e699.  This
change broke a number of tests that assumed the previous behavior.


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<tr class='logheader'><td><span title='2022-10-07 16:54:20 -0400'>2022-10-07</span></td><td class='logsubject'><a href='/guix/commit/nix?id=bb0beaecdee1a2315a1269b1746d238c8ab0e699'>nix: Guard against removing temporary roots of living processes.</a></td><td>Ludovic Courtès</td></tr>
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Fixes &lt;https://issues.guix.gnu.org/25018&gt;.

* nix/libstore/gc.cc (readTempRoots): Add a check to guard against removing
the temporary roots of a living process.

Signed-off-by: Maxim Cournoyer &lt;maxim.cournoyer@gmail.com&gt;


</td></tr>
<tr class='logheader'><td><span title='2022-09-11 16:43:30 +0200'>2022-09-11</span></td><td class='logsubject'><a href='/guix/commit/nix?id=4b32f87e9adf91d5d94287562d8844727d47a07b'>daemon: Remove unused function findOutput.</a></td><td>Maxime Devos</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* nix/libstore/misc.cc (findOutput): Remove it.
* nix/libstore/misc.hh (findOutput): Likewise.

Signed-off-by: Mathieu Othacehe &lt;othacehe@gnu.org&gt;


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<tr class='logheader'><td><span title='2022-09-11 16:43:30 +0200'>2022-09-11</span></td><td class='logsubject'><a href='/guix/commit/nix?id=93032586df6b925e1ed9102dc3a77aa626aa60d3'>daemon: Remove unused function exportPaths.</a></td><td>Maxime Devos</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* nix/libstore/store-api.cc (exportPaths): Remove it.
* nix/libstore/store-api.hh (exportPaths): Likewise.

Signed-off-by: Mathieu Othacehe &lt;othacehe@gnu.org&gt;


</td></tr>
<tr class='logheader'><td><span title='2022-09-11 16:43:30 +0200'>2022-09-11</span></td><td class='logsubject'><a href='/guix/commit/nix?id=1c5f5d6d8cb3bd42ed436e31366a328598165734'>daemon: Remove unused function openStore.</a></td><td>Maxime Devos</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* nix/libstore/store-api.cc (openStore): Remove it.
* nix/libstore/store-api.hh (openStore): Likewise.

Signed-off-by: Mathieu Othacehe &lt;othacehe@gnu.org&gt;


</td></tr>