Arm: Fix arm libsanitizer bootstrap failure

Glibc has recently introduced changed to the mode field in ipc_perm
in commit 2f959dfe849e0646e27403f2e4091536496ac0f0. For Arm this
means that the mode field no longer has the same size.

This causes an assert failure against libsanitizer's internal copy
of ipc_perm.  Since this change can't be easily detected I am adding
arm to the list of targets that are excluded from this check.  libsanitizer
doesn't use this field (and others, it in fact uses only 1 field) so this check
can be ignored.

Padding bits were used by glibc when the field was changed so sizeof and offsets
of the remaining fields should be the same.

libsanitizer/ChangeLog:

	PR sanitizer/92154
	* sanitizer_common/sanitizer_platform_limits_posix.cpp (defined):
	Cherry-pick compiler-rt revision r375220.

From-SVN: r277291

libsanitizer/ChangeLog

+2019-10-22  Tamar Christina  <tamar.christina@arm.com>
+
+	PR sanitizer/92154
+	* sanitizer_common/sanitizer_platform_limits_posix.cpp:
+	Cherry-pick compiler-rt revision r375220.
+
 2019-09-27  Maciej W. Rozycki  <macro@wdc.com>
 
 	* configure: Regenerate.

libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cpp

@@ -1126,8 +1126,12 @@ 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)
+#if (!defined(__aarch64__) || !SANITIZER_LINUX || __GLIBC_PREREQ (2, 21)) && \
+    !defined(__arm__)
 /* On aarch64 glibc 2.20 and earlier provided incorrect mode field.  */
+/* On Arm glibc 2.31 and later provide a different mode field, this field is
+   never used by libsanitizer so we can simply ignore this assert for all glibc
+   versions.  */
 CHECK_SIZE_AND_OFFSET(ipc_perm, mode);
 #endif