Adjust libsanitizer to ABI change in glibc 2.31.

Adapted to 3.x from this upstream commit:
https://github.com/llvm/llvm-project/commit/947f9692440836dcb8d88b74b69dd379d85974ce

--- a/lib/sanitizer_common/saniniitizer_platform_limits_posix.h.orig	2020-08-11 16:01:32.494882282 +0200 #
+++ b/lib/sanitizer_common/sanitizer_platform_limits_posix.h	2020-08-11 16:32:49.711383554 +0200
@@ -176,8 +176,7 @@
     unsigned long __unused1;
     unsigned long __unused2;
 #else
-    unsigned short mode;
-    unsigned short __pad1;
+    unsigned int mode;
     unsigned short __seq;
     unsigned short __pad2;
 #if defined(__x86_64__) && !defined(_LP64)
--- a/lib/sanitizer_common/sanitizer_platform_limits_posix.cc	2020-08-11 16:01:07.926821829 +0200
+++ b/lib/sanitizer_common/sanitizer_platform_limits_posix.cc.orig	2020-08-11 16:01:03.698811421 +0200
@@ -1056,7 +1056,9 @@
 CHECK_SIZE_AND_OFFSET(ipc_perm, gid);
 CHECK_SIZE_AND_OFFSET(ipc_perm, cuid);
 CHECK_SIZE_AND_OFFSET(ipc_perm, cgid);
+#if !SANITIZER_LINUX || __GLIBC_PREREQ (2, 31)
 CHECK_SIZE_AND_OFFSET(ipc_perm, mode);
+#endif
 
 CHECK_TYPE_SIZE(shmid_ds);
 CHECK_SIZE_AND_OFFSET(shmid_ds, shm_perm);
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<div class='path'>path: <a href='/guix/log/?id=f2c37028850fa03d6a25ae6c1d8366fe4b76374b'>root</a>/<a href='/guix/log/gnu?id=f2c37028850fa03d6a25ae6c1d8366fe4b76374b'>gnu</a>/<a href='/guix/log/gnu/services?id=f2c37028850fa03d6a25ae6c1d8366fe4b76374b'>services</a>/<a href='/guix/log/gnu/services/vpn.scm?id=f2c37028850fa03d6a25ae6c1d8366fe4b76374b'>vpn.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/vpn.scm?id=f2c37028850fa03d6a25ae6c1d8366fe4b76374b&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-02-19 04:08:55 +0100'>2020-02-19</span></td><td><a href='/guix/commit/gnu/services/vpn.scm?id=c6c447701c9cfdeedf77224399faa9c07b12d045'>gnu: services: Add openvpn options.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/vpn.scm (openvpn-client-configuration)
(openvpn-server-configuration): Add fast-io? and auth-user-pass options.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2020-02-19 04:08:40 +0100'>2020-02-19</span></td><td><a href='/guix/commit/gnu/services/vpn.scm?id=0372dd1a1e51e39382ee5d1aa968589b40506b8f'>gnu: services: Fix openvpn boolean fields.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/vpn.scm (serialize-boolean): Do not print #t to the file.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2017-10-10 22:06:08 +0200'>2017-10-10</span></td><td><a href='/guix/commit/gnu/services/vpn.scm?id=4b8b4418e609b5e0bfb6efbc11ac28deaa437e80'>services: vpn: Fix default tls-auth configuration.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/vpn.scm (serialize-tls-auth): Fix serialization error when
tls-auth is disabled.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2017-03-31 20:55:05 -0500'>2017-03-31</span></td><td><a href='/guix/commit/gnu/services/vpn.scm?id=9fc221b58cecd73e22cac01cb0918a774a4a7b2f'>doc: Fix typos.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/guix.texi (Build Systems)[ocaml-build-system]: Fix typo.
(Log Rotation)[periodic-rotations]: ditto.
(Database Services)[redis-service-type]: ditto.
(OpenSMTPD Service)[opensmtpd-configuration]: ditto.
(VPN Services)[OpenVPN]: ditto.
(Power management Services)[tlp-configuration]: ditto.
(Git daemon service)[git-daemon-service]: ditto.
(Running GuixSD in a VM): ditto.
* gnu/services/pm.scm (tlp-configuration)[runtime-pm-blacklist]: Fix typo.
* gnu/services/vpn.scm (openvpn-client-configuration)[status]: ditto.
</span></span></td><td>Eric Bavier</td></tr>
<tr><td><span title='2017-03-24 16:09:18 +0100'>2017-03-24</span></td><td><a href='/guix/commit/gnu/services/vpn.scm?id=85ac401acf2e33e4cb6d1510ac24867dc516e656'>services: openvpn: Fix a typo which was corrected in generated doc.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/vpn.scm (define-split-configuration): Fix typo.

Signed-off-by: Clément Lassieur &lt;clement@lassieur.org&gt;
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2017-01-25 14:05:37 +0100'>2017-01-25</span></td><td><a href='/guix/commit/gnu/services/vpn.scm?id=e57bd0bed86caac304e5f37c5653e6b13858c7c5'>services: Fix 'mkdir-p' in activation scripts.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/cups.scm (%cups-activation): Import (guix build utils).
* gnu/services/mail.scm (opensmtpd-activation): Idem.
* gnu/services/networking.scm (ntp-service-activation): Idem.
* gnu/services/spice.scm (spice-vdagent-activation): Idem.
* gnu/services/ssh.scm (openssh-activation): Idem.
  (dropbear-activation): Idem.
* gnu/services/vpn.scm (%openvpn-activation): Idem.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Clément Lassieur</td></tr>
<tr><td><span title='2017-01-20 21:39:17 +0100'>2017-01-20</span></td><td><a href='/guix/commit/gnu/services/vpn.scm?id=be051880c435d19e7788d5df56c062f7797e0a49'>services: Reindent vpn.scm.</a><span class='msg-avail'>...<span class='msg-tooltip'>This fixes indentation of 'match' forms.

* gnu/services/vpn.scm: Pass through 'indent-code.el'.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-01-15 12:24:52 +0100'>2017-01-15</span></td><td><a href='/guix/commit/gnu/services/vpn.scm?id=2be1b4712d362fa9face12a731e75038ae9d59ba'>gnu: Add openvpn service.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/vpn.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.
* doc/guix.texi (VPN Services): New section.
</span></span></td><td>Julien Lepiller</td></tr>