Stub out libevent's signal.c.

third_party/libevent/libevent_nacl_nonsfi.gyp

 # 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.
 
 {
   'includes': [
     '../../build/common_untrusted.gypi',
   ],
   'conditions': [
     ['disable_nacl==0 and disable_nacl_untrusted==0', {
       'targets': [
         {
           'target_name': 'event_nacl_nonsfi',
           'type': 'none',
           'sources': [
             'buffer.c',
             'evbuffer.c',
             'event.c',
             'evutil.c',
             'log.c',
             'poll.c',
-            'signal.c',
             'strlcpy.c',
             'nacl_nonsfi/config.h',
             'nacl_nonsfi/event-config.h',
             'nacl_nonsfi/random.c',
+            'nacl_nonsfi/signal_stub.c',
           ],
           'defines': [
             'HAVE_CONFIG_H',
           ],
           'include_dirs': [
             'nacl_nonsfi',
           ],
           'variables': {
             'nacl_untrusted_build': 1,
             'nlib_target': 'libevent_nacl_nonsfi.a',
             'build_glibc': 0,
             'build_newlib': 0,
             'build_irt': 0,
             'build_pnacl_newlib': 0,
             'build_nonsfi_helper': 1,
           },
           'dependencies': [
             '../../native_client/tools.gyp:prep_toolchain',
           ],
         },
       ],
     }],
   ],
 }