Fourth attempt at the following. Unreviewed, this was originally reviewed in http://codereview.c...

third_party/libevent/libevent.gyp

 # Copyright (c) 2011 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': {
     'use_system_libevent%': 0,
   },
   'conditions': [
     ['use_system_libevent==0', {
       'targets': [
         {
           'target_name': 'libevent',
           'product_name': 'event',
           'type': 'static_library',
+          'toolsets': ['host', 'target'],
           'sources': [
             'buffer.c',
             'evbuffer.c',
             'evdns.c',
             'event.c',
             'event_tagging.c',
             'evrpc.c',
             'evutil.c',
             'http.c',
             'log.c',
@@ skipping 56 matching lines @@
           'link_settings': {
             'libraries': [
               '-levent',
             ],
           },
         }
       ],
     }],
   ],
 }