win: Add implementation of system_snapshot for Windows

compat/compat.gyp

 # Copyright 2014 The Crashpad Authors. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
 #     http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 13 matching lines @@
         'mac/mach-o/getsect.h',
         'mac/mach-o/loader.h',
         'non_mac/mach/mach.h',
         'non_win/dbghelp.h',
         'non_win/minwinbase.h',
         'non_win/timezoneapi.h',
         'non_win/verrsrc.h',
         'non_win/windows.h',
         'non_win/winnt.h',
         'win/sys/types.h',
+        'win/winnt.h',
       ],
       'conditions': [
         ['OS=="mac"', {
           'dependencies': [
             '../third_party/apple_cctools/apple_cctools.gyp:apple_cctools',
           ],
           'include_dirs': [
             'mac',
           ],
           'direct_dependent_settings': {
@@ skipping 18 matching lines @@
           'direct_dependent_settings': {
             'include_dirs': [
               'non_win',
             ],
           },
         }],
       ],
     },
   ],
 }