Revert of Reland: Introduce sys_sigprocmask and sys_sigaction.

sandbox/linux/seccomp-bpf/trap_unittest.cc

-// Copyright 2015 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.
-
-#include "sandbox/linux/seccomp-bpf/trap.h"
-
-#include <signal.h>
-
-#include "sandbox/linux/tests/unit_tests.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-namespace sandbox {
-namespace {
-
-SANDBOX_TEST_ALLOW_NOISE(Trap, SigSysAction) {
-  // This creates a global Trap instance, and registers the signal handler
-  // (Trap::SigSysAction).
-  Trap::Registry();
-
-  // Send SIGSYS to self. If signal handler (SigSysAction) is not registered,
-  // the process will be terminated with status code -SIGSYS.
-  // Note that, SigSysAction handler would output an error message
-  // "Unexpected SIGSYS received." so it is necessary to allow the noise.
-  raise(SIGSYS);
-}
-
-}  // namespace
-}  // namespace sandbox