sandbox arm64: align stack 16 bytes

sandbox/linux/services/credentials.cc

Index: sandbox/linux/services/credentials.cc
diff --git a/sandbox/linux/services/credentials.cc b/sandbox/linux/services/credentials.cc
index fb6b6b4acab163b33054c8fd63eb004e3a73a268..76038af45b8b59767ca7dc8da1b83c4d50b6a915 100644
--- a/sandbox/linux/services/credentials.cc
+++ b/sandbox/linux/services/credentials.cc
@@ -16,6 +16,7 @@
 #include <unistd.h>
 
 #include "base/bind.h"
+#include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
@@ -94,7 +95,7 @@ bool ChrootToSafeEmptyDir() {
   // /proc/tid directory for the thread (since /proc may not be aware of the
   // PID namespace). With a process, we can just use /proc/self.
   pid_t pid = -1;
-  char stack_buf[PTHREAD_STACK_MIN];
+  char stack_buf[PTHREAD_STACK_MIN] ALIGNAS(16);
 #if defined(ARCH_CPU_X86_FAMILY) || defined(ARCH_CPU_ARM_FAMILY) || \
     defined(ARCH_CPU_MIPS64_FAMILY) || defined(ARCH_CPU_MIPS_FAMILY)
   // The stack grows downward.