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;
s='sub'>Wojtek's customized Guix</td><td class='sub right'></td></tr></table>
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<div class='path'>path: <a href='/guix/log/?id=79b2221ce43b8026eae6461a9269466cae946cac'>root</a>/<a href='/guix/log/gnu?id=79b2221ce43b8026eae6461a9269466cae946cac'>gnu</a>/<a href='/guix/log/gnu/services?id=79b2221ce43b8026eae6461a9269466cae946cac'>services</a>/<a href='/guix/log/gnu/services/lightdm.scm?id=79b2221ce43b8026eae6461a9269466cae946cac'>lightdm.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/lightdm.scm?id=79b2221ce43b8026eae6461a9269466cae946cac&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-02-08 22:40:40 -0500'>2023-02-08</span></td><td><a href='/guix/commit/gnu/services/lightdm.scm?id=8a2c2eaa906bd12d9c804ba18ac305b9719507ef'>services: lightdm: Sync documentation with source.</a><span class='msg-avail'>...<span class='msg-tooltip'>Table entry @item nodes cannot span multiple lines.

* gnu/services/lightdm.scm
(lightdm-gtk-greeter-configuration): Fix cursor-theme-size description.
* doc/guix.texi (lightdm-service-type): Sync with source.

Signed-off-by: Maxim Cournoyer &lt;maxim.cournoyer@gmail.com&gt;
</span></span></td><td>Bruno Victal</td></tr>
<tr><td><span title='2022-11-19 19:54:14 +0100'>2022-11-19</span></td><td><a href='/guix/commit/gnu/services/lightdm.scm?id=50c17ddd9e2983d71c125d89b422fd20fca476e1'>services: lightdm: Do not use GOOPS.</a><span class='msg-avail'>...<span class='msg-tooltip'>There's an unwritten policy to not use GOOPS in Guix.

* gnu/services/lightdm.scm (strip-class-name-brackets): Rename to...
(strip-record-type-name-brackets): ... this.
(config-&gt;name): Adjust accordingly and use 'record-type-name' instead of
'class-name'.
(list-of-greeter-configurations?): Likewise.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-10-23 17:03:09 -0700'>2022-10-23</span></td><td><a href='/guix/commit/gnu/services/lightdm.scm?id=d3e982dccbd8ec7e00a2ab3efa04bef8f1c16b9e'>gnu: Fix typos.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/emacs-xyz.scm (emacs-piem)[description]: Fix use of "This
  packages".
* gnu/packages/tex.scm (texlive-hardwrap)[description]: Fix spelling of
  "arbitrary".
* gnu/packages/cran.scm (r-shinymanager)[description]: Fix spelling of
  "authentication".
* gnu/packages/lisp-xyz.scm (sbcl-utils-kt)[description]: Fix spelling of
  "developed".
* gnu/packages/crates-io.scm (rust-fs-utils-1)[description]: Fix spelling of
  "filesystem".
  [synopsis]: Likewise.
* gnu/packages/haxe.scm (neko)[description]: Fix spelling of "functions".
* gnu/packages/animation.scm (swftools)[description]: Fix needless
  pluralization of "information".
* gnu/packages/lisp-xyz.scm (sbcl-slot-extra-options)[description]: Fix
  spelling of "inheritance".
* gnu/packages/emacs-xyz.scm (emacs-js-comint)[description]: Fix spelling of
  "interpreter".
* gnu/packages/coq.scm (coq-mathcomp-finmap)[description]: Fix spelling of
  "library".
* gnu/services/lightdm.scm (lightdm-configuration): Fix spelling of
  "mechanism".
* gnu/packages/emacs-xyz.scm (emacs-citar-org-roam)[synopsis]: Fix spelling of
  "package".
* gnu/packages/games.scm (freerct)[description]: Fix spelling of
  "responsibilities".
* gnu/packages/statistics.scm (r-mixedpower)[description]: Fix spelling of
  "separate".
* gnu/packages/accessibility.scm (espeakup)[description]: Fix spelling of
  "speech".
* gnu/packages/bioinformatics.scm (r-skitools)[synopsis]: Fix spelling of
  "utilities".
* gnu/packages/golang.scm (go-github-com-savsgio-gotils)[synopsis]: Fix
  spelling of "utilities".
  [description]: Likewise.
* gnu/system.scm (boot-file-system-service os): Fix spelling of "utilities".
</span></span></td><td>Vagrant Cascadian</td></tr>
<tr><td><span title='2022-08-28 22:28:47 -0400'>2022-08-28</span></td><td><a href='/guix/commit/gnu/services/lightdm.scm?id=0ea62e84a787fe94cfeadf67ef27ea995a382b84'>services: Add lightdm-service-type.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/lightdm.scm: New service.
* tests/services/lightdm.scm: Test it.
* doc/guix.texi (X Window): Document it.
* gnu/local.mk (GNU_SYSTEM_MODULES): Register it.

Co-authored-by: L p R n d n &lt;guix@lprndn.info&gt;
Co-authored-by: Ricardo Wurmus &lt;rekado@elephly.net&gt;
</span></span></td><td>Maxim Cournoyer</td></tr>