Fix sanitizer-common build with glibc 2.31

[jakubjelinek]

Summary

As mentioned in D69104, glibc changed ABI recently with the 2f959dfe change.
D69104 dealt with just 32-bit ARM, but that is just one of the many affected architectures.
E.g. x86_64, i?86, riscv64, sparc 32-bit, s390 31-bit are affected too (and various others).

This patch instead of adding a long list of further architectures that wouldn't be checked ever next to arm 32-bit changes the structures to match the 2.31 layout and performs the checking on Linux for ipc_perm mode position/size only on non-Linux or on Linux with glibc 2.31 or later. I think this matches what is done for aarch64 already.
If needed, we could list architectures that haven't changed ABI (e.g. powerpc), so that they would be checked even with older glibcs. AFAIK sanitizers don't actually use ipc_perm.mode and
so all they care about is the size and alignment of the whole structure.

Note, s390 31-bit and arm 32-bit big-endian changed ABI even further, there will now be shmctl with old symbol version and shmctl@@GLIBC_2.31 which will be incompatible. I'm afraid this isn't really solvable unless the sanitizer libraries are symbol versioned and use matching symbol versions to glibc symbols for stuff they intercept, plus use dlvsym.
This patch doesn't try to address that.

[eugenis]

LGTM

[jakubjelinek]

Can somebody please commit it? I don't have access to llvm repo. Thanks.

compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_posix.h

struct __sanitizer_ipc_perm {
   int cuid;
   int cgid;
 #ifdef __powerpc__
   unsigned mode;
   unsigned __seq;
   u64 __unused1;
   u64 __unused2;
 #elif defined(__sparc__)
-#if defined(__arch64__)
   unsigned mode;
-  unsigned short __pad1;
-#else
-  unsigned short __pad1;
-  unsigned short mode;
   unsigned short __pad2;
-#endif
   unsigned short __seq;
   unsigned long long __unused1;
   unsigned long long __unused2;
-#elif defined(__mips__) || defined(__aarch64__) || defined(__s390x__)
-  unsigned int mode;
-  unsigned short __seq;
-  unsigned short __pad1;
-  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)
   u64 __unused1;
   u64 __unused2;
 #else
   unsigned long __unused1;
   unsigned long __unused2;

compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_posix.cpp

 # else
 CHECK_SIZE_AND_OFFSET(ipc_perm, __key);
 CHECK_SIZE_AND_OFFSET(ipc_perm, __seq);
 # endif
 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)) && \
-    !defined(__arm__)
-/* On aarch64 glibc 2.20 and earlier provided incorrect mode field.  */
-/* On Arm newer glibc provide a different mode field, it's hard to detect
-   so just disable the check.  */
+#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
 
 CHECK_TYPE_SIZE(shmid_ds);
 CHECK_SIZE_AND_OFFSET(shmid_ds, shm_perm);
 CHECK_SIZE_AND_OFFSET(shmid_ds, shm_segsz);
 CHECK_SIZE_AND_OFFSET(shmid_ds, shm_atime);
 CHECK_SIZE_AND_OFFSET(shmid_ds, shm_dtime);