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
@@ -1139,8 +1139,9 @@ CHECK_SIZE_AND_OFFSET(ipc_perm, uid);
 CHECK_SIZE_AND_OFFSET(ipc_perm, gid);
 CHECK_SIZE_AND_OFFSET(ipc_perm, cuid);
 CHECK_SIZE_AND_OFFSET(ipc_perm, cgid);
-#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/compiler-rt/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
@@ -194,17 +194,16 @@ namespace __sanitizer {
     unsigned __seq;
     u64 __unused1;
     u64 __unused2;
-#elif defined(__mips__) || defined(__aarch64__) || defined(__s390x__)
-    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;
oot</a>/<a href='/guix/log/.mailmap?id=c85c85d67cd2d2c516e180ff334e865c3d64c437'>.mailmap</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/.mailmap?id=c85c85d67cd2d2c516e180ff334e865c3d64c437&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-05-15 09:08:46 +0200'>2020-05-15</span></td><td><a href='/guix/commit/.mailmap?id=dff31d41d945bf4b25ad3014dac32561bfbb33a0'>mailmap: Update for self.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-05-13 09:30:26 +0300'>2020-05-13</span></td><td><a href='/guix/commit/.mailmap?id=3c986a7dc268756c097212de958f046b29b76c1b'>mailmap: Update entries for Nikita.</a><span class='msg-avail'>...</span></td><td>nikita</td></tr>
<tr><td><span title='2020-03-28 16:30:07 -0400'>2020-03-28</span></td><td><a href='/guix/commit/.mailmap?id=c2cf286c62933d2806ae17b8287520820bf87c7e'>Update email address and Savannah handle for Amin Bandali.</a><span class='msg-avail'>...</span></td><td>Amin Bandali</td></tr>
<tr><td><span title='2020-02-09 23:16:45 +0100'>2020-02-09</span></td><td><a href='/guix/commit/.mailmap?id=e81344428726f3dae5d2a2e7bb296f46fcde6cc5'>Update e-mail address for Jakob L. Kreuze.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-01-17 18:30:33 +0100'>2020-01-17</span></td><td><a href='/guix/commit/.mailmap?id=a3143063aeeecb5c02f75a6e1ddc0cc295e0e4f8'>Update email address for Amin Bandali.</a><span class='msg-avail'>...</span></td><td>Amin Bandali</td></tr>
<tr><td><span title='2019-12-19 11:35:23 -0600'>2019-12-19</span></td><td><a href='/guix/commit/.mailmap?id=4b3ff36228da17db980c98fe9e1669be613a5402'>Update email for Brett Gilio.</a><span class='msg-avail'>...</span></td><td>Brett Gilio</td></tr>
<tr><td><span title='2019-12-18 22:57:44 -0600'>2019-12-18</span></td><td><a href='/guix/commit/.mailmap?id=a7cdf124c0b28be6c4e750161c1341753eede7b8'>gnu: leocad: Update to 19.07.1.</a><span class='msg-avail'>...</span></td><td>Eric Bavier</td></tr>
<tr><td><span title='2019-05-03 08:45:55 +0200'>2019-05-03</span></td><td><a href='/guix/commit/.mailmap?id=3e85909044d8d9b492bcd2ecedde26d71794f145'>Correct email address for ison.</a><span class='msg-avail'>...</span></td><td>ison</td></tr>
<tr><td><span title='2019-03-18 15:05:08 +0100'>2019-03-18</span></td><td><a href='/guix/commit/.mailmap?id=47956fa0c24efcdcba3493f0231c30e9a39ec7df'>Correct name and email address for ng0.</a><span class='msg-avail'>...</span></td><td>ng0</td></tr>