Fix CVE-2019-19126:

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-19126
https://sourceware.org/bugzilla/show_bug.cgi?id=25204

Taken from upstream:
https://sourceware.org/git/?p=glibc.git;a=commit;h=37c90e117310728a4ad1eb998c0bbe7d79c4a398

diff --git a/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h b/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h
index 975cbe2..df2cdfd 100644
--- a/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h
+++ b/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h
@@ -31,7 +31,8 @@
    environment variable, LD_PREFER_MAP_32BIT_EXEC.  */
 #define EXTRA_LD_ENVVARS \
   case 21:								  \
-    if (memcmp (envline, "PREFER_MAP_32BIT_EXEC", 21) == 0)		  \
+    if (!__libc_enable_secure						  \
+	&& memcmp (envline, "PREFER_MAP_32BIT_EXEC", 21) == 0)		  \
       GLRO(dl_x86_cpu_features).feature[index_arch_Prefer_MAP_32BIT_EXEC] \
 	|= bit_arch_Prefer_MAP_32BIT_EXEC;				  \
     break;
ub'>Wojtek's customized Guix</td><td class='sub right'></td></tr></table>
<table class='tabs'><tr><td>
<a href='/guix/about/'>about</a><a href='/guix/'>summary</a><a href='/guix/refs/?id=4914846012392f5653d11ba9a94da175f70abe9f'>refs</a><a class='active' href='/guix/log/gnu/services/linux.scm'>log</a><a href='/guix/tree/gnu/services/linux.scm?id=4914846012392f5653d11ba9a94da175f70abe9f'>tree</a><a href='/guix/commit/gnu/services/linux.scm?id=4914846012392f5653d11ba9a94da175f70abe9f'>commit</a><a href='/guix/diff/gnu/services/linux.scm?id=4914846012392f5653d11ba9a94da175f70abe9f'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/services/linux.scm'>
<input type='hidden' name='id' value='4914846012392f5653d11ba9a94da175f70abe9f'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=4914846012392f5653d11ba9a94da175f70abe9f'>root</a>/<a href='/guix/log/gnu?id=4914846012392f5653d11ba9a94da175f70abe9f'>gnu</a>/<a href='/guix/log/gnu/services?id=4914846012392f5653d11ba9a94da175f70abe9f'>services</a>/<a href='/guix/log/gnu/services/linux.scm?id=4914846012392f5653d11ba9a94da175f70abe9f'>linux.scm</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/gnu/services/linux.scm?id=4914846012392f5653d11ba9a94da175f70abe9f&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2021-04-24 12:30:01 -0400'>2021-04-24</span></td><td><a href='/guix/commit/gnu/services/linux.scm?id=2c93df3d11bf8ceeb5c203416a2533cf32275e1a'>services: Add a service for rasdaemon.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/linux.scm (rasdaemon-configuration, rasdaemon-configuration?,
rasdaemon-configuration-record?, rasdaemon-service-type): New variables.
* doc/guix.texi (Linux Services): Document it.

Signed-off-by: Leo Famulari &lt;leo@famulari.name&gt;
</span></span></td><td>B. Wilson</td></tr>
<tr><td><span title='2021-02-08 03:34:40 +0100'>2021-02-08</span></td><td><a href='/guix/commit/gnu/services/linux.scm?id=fe7529d71b8d7b09b48679c86e1155895afd92a4'>gnu: Remove 'file-systems requirement from kernel-module-loader.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/linux.scm (kernel-module-loader-shepherd-service):
Remove 'file-systems requirement.

Signed-off-by: Danny Milosavljevic &lt;dannym@scratchpost.org&gt;
</span></span></td><td>raid5atemyhomework</td></tr>
<tr><td><span title='2021-01-06 19:18:58 +0100'>2021-01-06</span></td><td><a href='/guix/commit/gnu/services/linux.scm?id=3d3185b54448cb44fffc1badc8c1cf51bb76585d'>services: kernel-module-loader: Return a single 'shepherd-service'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/linux.scm (kernel-module-loader-shepherd-service): Return
a 'shepherd-service' instead of a list of it.
(kernel-module-loader-service-type): Adjust it.

Signed-off-by: Danny Milosavljevic &lt;dannym@scratchpost.org&gt;
</span></span></td><td>Brice Waegeneire</td></tr>
<tr><td><span title='2020-09-13 23:07:36 +0200'>2020-09-13</span></td><td><a href='/guix/commit/gnu/services/linux.scm?id=71992a532dd0bb88b39dda285482b332a24dae66'>services: Fix zram-device-service.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/linux.scm (&lt;zram-device-configuration&gt;): Fix typo.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-08-02 15:54:37 +0300'>2020-08-02</span></td><td><a href='/guix/commit/gnu/services/linux.scm?id=587e0d911dfff81647015e89847084b606e68f71'>services: Add zram-device-service.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/linux.scm (&lt;zram-device-configuration&gt;): New record.
(zram-device-service-type): New variable.
* doc/guix.texi (Linux Services): Document it.
* tests/services/linux.scm (zram-swap-device-test): New tests.
</span></span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2020-04-12 18:24:27 +0000'>2020-04-12</span></td><td><a href='/guix/commit/gnu/services/linux.scm?id=8e4d1493f1d56e29252eb7a36b3eee2a0e073ee4'>services: kernel-module-loader: Clean up.</a><span class='msg-avail'>...<span class='msg-tooltip'>Suggested by Efraim Flashner &lt;efraim@flashner.co.il&gt;.
See &lt;https://lists.gnu.org/archive/html/bug-guix/2020-04/msg00237.html&gt;.

* gnu/services/linux.scm (kernel-module-loader-shepherd-service):
Remove unneeded 'respawn?' field.
</span></span></td><td>Florian Pelz</td></tr>
<tr><td><span title='2020-04-05 13:07:13 +0200'>2020-04-05</span></td><td><a href='/guix/commit/gnu/services/linux.scm?id=044d1478c9a63a64547c9cc320008f8d8fbf6791'>gnu: Add kernel-module-loader-service.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/guix.texi (Linux Services): Add a new subsection and document the
new service and its configuration.
* gnu/services/linux.scm (kernel-module-loader-service-type): New type.
(kernel-module-loader-shepherd-service): New procedure.
* gnu/tests/linux-modules.scm (module-loader-program): Procedure
removed.
(modules-loaded?-program): New procedure.
(run-loadable-kernel-modules-test): 'module-loader-program' procedure
replaced by the new one.
[os]: Use 'kernel-module-loader-service'.

Signed-off-by: Danny Milosavljevic &lt;dannym@scratchpost.org&gt;
</span></span></td><td>Brice Waegeneire</td></tr>
<tr><td><span title='2020-01-31 23:37:13 -0500'>2020-01-31</span></td><td><a href='/guix/commit/gnu/services/linux.scm?id=d3e439e355284f136ff13eb3e6fffb4661552f3b'>gnu: Add earlyoom-service-type.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/linux.scm: New file.
* tests/services/linux.scm: Add test.
* Makefile.am (SCM_TESTS): Register test.
* doc/guix.texi (Linux Services): Add a new section and document the new
service and its configuration.
</span></span></td><td>Maxim Cournoyer</td></tr>