[NaCl SDK] Remove stubs for sitaddset/sigdelset and friends.

native_client_sdk/src/libraries/nacl_io/syscalls/sigdelset.c

Index: native_client_sdk/src/libraries/nacl_io/syscalls/sigdelset.c
diff --git a/native_client_sdk/src/libraries/nacl_io/syscalls/sigdelset.c b/native_client_sdk/src/libraries/nacl_io/syscalls/sigdelset.c
deleted file mode 100644
index b595320fc9720ff93213eddb60b14abf52c53f49..0000000000000000000000000000000000000000
--- a/native_client_sdk/src/libraries/nacl_io/syscalls/sigdelset.c
+++ /dev/null
@@ -1,13 +0,0 @@
-/* Copyright 2013 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 "nacl_io/kernel_intercept.h"
-#include "nacl_io/kernel_wrap.h"
-
-#if defined(__native_client__) && !defined(__GLIBC__) && !defined(__BIONIC__)
-int sigdelset(sigset_t* set, const int signum) {
-  *set &= ~(1 << signum);
-  return 0;
-}
-#endif