Merge commit 'f8b497ef611b' from llvm.org/main into next

Author: git apple-llvm automerger

compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_posix.h

@@ -601,7 +601,7 @@ struct __sanitizer_siginfo_pad {
 #if SANITIZER_LINUX
 # define SANITIZER_HAS_SIGINFO 1
 union __sanitizer_siginfo {
-  struct {
+  __extension__ struct {
     int si_signo;
 # if SANITIZER_MIPS
     int si_code;