Introduce sys_sigprocmask and sys_sigaction.

sandbox/linux/sandbox_linux.gypi

 # 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.
 
 {
   'variables': {
     'conditions': [
       ['OS=="linux"', {
         'compile_suid_client': 1,
         'compile_credentials': 1,
@@ skipping 260 matching lines @@
           ],
         }],
       ],
       'include_dirs': [
         '..',
       ],
     },
     { 'target_name': 'sandbox_services_headers',
       'type': 'none',
       'sources': [
-        'system_headers/android_arm64_ucontext.h',
-        'system_headers/android_arm_ucontext.h',
         'system_headers/android_futex.h',
-        'system_headers/android_i386_ucontext.h',
-        'system_headers/android_mips_ucontext.h',
-        'system_headers/android_ucontext.h',
         'system_headers/arm64_linux_syscalls.h',
+        'system_headers/arm64_linux_ucontext.h',
         'system_headers/arm_linux_syscalls.h',
+        'system_headers/arm_linux_ucontext.h',
         'system_headers/capability.h',
+        'system_headers/i386_linux_ucontext.h',
         'system_headers/linux_seccomp.h',
         'system_headers/linux_syscalls.h',
+        'system_headers/linux_ucontext.h',
         'system_headers/mips_linux_syscalls.h',
+        'system_headers/mips_linux_ucontext.h',
         'system_headers/x86_32_linux_syscalls.h',
         'system_headers/x86_64_linux_syscalls.h',
       ],
       'include_dirs': [
         '..',
       ],
     },
     {
       # We make this its own target so that it does not interfere
       # with our tests.
@@ skipping 93 matching lines @@
             '../../build/isolate.gypi',
           ],
           'sources': [
             '../sandbox_linux_unittests.isolate',
           ],
         },
       ],
     }],
   ],
 }