Switch to standard integer types in sandbox/.

sandbox/linux/system_headers/arm64_linux_ucontext.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SANDBOX_LINUX_SYSTEM_HEADERS_ARM64_LINUX_UCONTEXT_H_
 #define SANDBOX_LINUX_SYSTEM_HEADERS_ARM64_LINUX_UCONTEXT_H_
 
 #if !defined(__BIONIC_HAVE_UCONTEXT_T)
 #include <asm/sigcontext.h>
 #include <signal.h>
+#include <stdint.h>
 // We also need greg_t for the sandbox, include it in this header as well.
 typedef uint64_t greg_t;
 
 struct ucontext_t {
   unsigned long uc_flags;
   struct ucontext* uc_link;
   stack_t uc_stack;
   sigset_t uc_sigmask;
   /* glibc uses a 1024-bit sigset_t */
   uint8_t unused[1024 / 8 - sizeof(sigset_t)];
   /* last for future expansion */
   struct sigcontext uc_mcontext;
 };
 
 #else
 #include <sys/ucontext.h>
 #endif  // __BIONIC_HAVE_UCONTEXT_T
 
 #endif  // SANDBOX_LINUX_SYSTEM_HEADERS_ARM64_LINUX_UCONTEXT_H_