Update from https://crrev.com/327068

sandbox/linux/system_headers/android_x86_64_ucontext.h

Index: sandbox/linux/system_headers/android_x86_64_ucontext.h
diff --git a/sandbox/linux/system_headers/android_x86_64_ucontext.h b/sandbox/linux/system_headers/android_x86_64_ucontext.h
deleted file mode 100644
index 778e6d073bb2905e218b5e90248aad17a43d0a89..0000000000000000000000000000000000000000
--- a/sandbox/linux/system_headers/android_x86_64_ucontext.h
+++ /dev/null
@@ -1,88 +0,0 @@
-// 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_ANDROID_X86_64_UCONTEXT_H_
-#define SANDBOX_LINUX_SYSTEM_HEADERS_ANDROID_X86_64_UCONTEXT_H_
-
-// We do something compatible with glibc. Hopefully, at some point Android will
-// provide that for us, and __BIONIC_HAVE_UCONTEXT_T should be defined.
-// Spec:
-// http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-AMD64/LSB-Core-AMD64/libc-ddefs.html#AEN5668
-
-#if !defined(__BIONIC_HAVE_UCONTEXT_T)
-#include <asm/sigcontext.h>
-
-struct _libc_fpxreg {
-  unsigned short significand[4];
-  unsigned short exponent;
-  unsigned short padding[3];
-};
-
-struct _libc_xmmreg {
-  uint32_t element[4];
-};
-
-struct _libc_fpstate {
-  uint16_t cwd;
-  uint16_t swd;
-  uint16_t twd;
-  uint16_t fop;
-  uint64_t rip;
-  uint64_t rdp;
-  uint32_t mxcsr;
-  uint32_t mxcsr_mask;
-  struct _libc_fpxreg _st[8];
-  struct _libc_xmmreg _xmm[16];
-  uint32_t padding[24];
-};
-
-typedef uint64_t greg_t;
-
-typedef struct {
-  greg_t gregs[23];
-  struct _libc_fpstate* fpregs;
-  unsigned long __reserved1[8];
-} mcontext_t;
-
-enum {
-  REG_R8 = 0,
-  REG_R9,
-  REG_R10,
-  REG_R11,
-  REG_R12,
-  REG_R13,
-  REG_R14,
-  REG_R15,
-  REG_RDI,
-  REG_RSI,
-  REG_RBP,
-  REG_RBX,
-  REG_RDX,
-  REG_RAX,
-  REG_RCX,
-  REG_RSP,
-  REG_RIP,
-  REG_EFL,
-  REG_CSGSFS,
-  REG_ERR,
-  REG_TRAPNO,
-  REG_OLDMASK,
-  REG_CR2,
-  NGREG,
-};
-
-typedef struct ucontext {
-  unsigned long uc_flags;
-  struct ucontext* uc_link;
-  stack_t uc_stack;
-  mcontext_t uc_mcontext;
-  sigset_t uc_sigmask;
-  struct _libc_fpstate __fpregs_mem;
-} ucontext_t;
-
-#else
-#include <sys/ucontext.h>
-#endif  // __BIONIC_HAVE_UCONTEXT_T
-
-#endif  // SANDBOX_LINUX_SYSTEM_HEADERS_ANDROID_X86_64_UCONTEXT_H_