WIP: Implement seccomp-bpf sandbox for nacl_helper_nonsfi.

sandbox/linux/system_headers/android_i386_ucontext.h

 // Copyright (c) 2012 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_I386_UCONTEXT_H_
 #define SANDBOX_LINUX_SYSTEM_HEADERS_ANDROID_I386_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.
 // This is mostly copied from breakpad (common/android/include/sys/ucontext.h),
 // except we do use sigset_t for uc_sigmask instead of a custom type.
 
 #if !defined(__BIONIC_HAVE_UCONTEXT_T)
+#if defined(__ANDORID__)
 #include <asm/sigcontext.h>
+#else
+typedef struct sigaltstack {
+  void* ss_sp;
+  int ss_flags;
+  size_t ss_size;
+} stack_t;
+#endif
 
 /* 80-bit floating-point register */
 struct _libc_fpreg {
   unsigned short significand[4];
   unsigned short exponent;
 };
 
 /* Simple floating-point state, see FNSTENV instruction */
 struct _libc_fpstate {
   unsigned long cw;
@@ skipping 45 matching lines @@
   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_I386_UCONTEXT_H_