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

diff --git a/lib/sanitizer_common/sanitizer_platform_limits_posix.cc b/lib/sanitizer_common/sanitizer_platform_limits_posix.cc
--- a/lib/sanitizer_common/sanitizer_platform_limits_posix.cc
+++ b/lib/sanitizer_common/sanitizer_platform_limits_posix.cc
@@ -1130,8 +1130,9 @@ CHECK_SIZE_AND_OFFSET(ipc_perm, cgid);
 #ifndef __GLIBC_PREREQ
 #define __GLIBC_PREREQ(x, y) 0
 #endif
-#if !defined(__aarch64__) || !SANITIZER_LINUX || __GLIBC_PREREQ (2, 21)
-/* On aarch64 glibc 2.20 and earlier provided incorrect mode field.  */
+#if !SANITIZER_LINUX || __GLIBC_PREREQ (2, 31)
+/* glibc 2.30 and earlier provided 16-bit mode field instead of 32-bit
+   on many architectures.  */
 CHECK_SIZE_AND_OFFSET(ipc_perm, mode);
 #endif
 
diff --git a/lib/sanitizer_common/sanitizer_platform_limits_posix.h b/lib/sanitizer_common/sanitizer_platform_limits_posix.h
--- a/lib/sanitizer_common/sanitizer_platform_limits_posix.h
+++ b/lib/sanitizer_common/sanitizer_platform_limits_posix.h
@@ -188,17 +188,16 @@ namespace __sanitizer {
     unsigned __seq;
     u64 __unused1;
     u64 __unused2;
-#elif defined(__mips__) || defined(__aarch64__)
-    unsigned int mode;
-    unsigned short __seq;
-    unsigned short __pad1;
-    unsigned long __unused1;
-    unsigned long __unused2;
+#elif defined(__sparc__)
+  unsigned mode;
+  unsigned short __pad2;
+  unsigned short __seq;
+  unsigned long long __unused1;
+  unsigned long long __unused2;
 #else
-    unsigned short mode;
-    unsigned short __pad1;
-    unsigned short __seq;
-    unsigned short __pad2;
+  unsigned int mode;
+  unsigned short __seq;
+  unsigned short __pad2;
 #if defined(__x86_64__) && !defined(_LP64)
     u64 __unused1;
     u64 __unused2;
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<div class='path'>path: <a href='/guix/log/?id=492e07ea6a19c644a72fca08a7b071d313f5843f'>root</a>/<a href='/guix/log/gnu?id=492e07ea6a19c644a72fca08a7b071d313f5843f'>gnu</a>/<a href='/guix/log/gnu/installer?id=492e07ea6a19c644a72fca08a7b071d313f5843f'>installer</a>/<a href='/guix/log/gnu/installer/tests.scm?id=492e07ea6a19c644a72fca08a7b071d313f5843f'>tests.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/installer/tests.scm?id=492e07ea6a19c644a72fca08a7b071d313f5843f&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-04-10 16:02:52 +0200'>2020-04-10</span></td><td><a href='/guix/commit/gnu/installer/tests.scm?id=475d48145d529be23d97b2bb92d2734365733bba'>installer: tests: Don't install to a CD/DVD.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/tests.scm (choose-partitioning): Use 'find' to select
the disk.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-03-26 11:53:50 +0100'>2020-03-26</span></td><td><a href='/guix/commit/gnu/installer/tests.scm?id=7a1a10dbd4ef2989ea1cac111849a36c567430e3'>installer: tests: Use a filter to select desktop-environments.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/tests.scm (choose-services): Turn desktop-environments list
into a choose-desktop-environment procedure. This way, it is easier to select
all desktop-environments or none, in the same way as choose-network-service?
and choose-network-management-tool? arguments.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-03-05 23:40:23 +0100'>2020-03-05</span></td><td><a href='/guix/commit/gnu/installer/tests.scm?id=ccb1a8c437fa40760899ae95f9d3f10ed7c8b41b'>tests: install: Add "gui-installed-os".</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/tests.scm: New file.
* gnu/local.mk (INSTALLER_MODULES): Add it.
* gnu/tests/install.scm (run-install): Add #:gui-test.  Add (gnu
installer tests) to the marionette imported modules.  Honor GUI-TEST.
Check whether SCRIPT is true.
(%root-password, %syslog-conf): New variable.
(operating-system-with-console-syslog, gui-test-program)
(guided-installation-test): New procedures.
(%extra-packages, installation-os-for-gui-tests)
(%test-gui-installed-os): New variable.
</span></span></td><td>Ludovic Courtès</td></tr>