win: Make reading NT_IMAGE_HEADERS work cross-bitness

snapshot/win/crashpad_snapshot_test_image_reader_module.cc

 // Copyright 2015 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,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <stdlib.h>
+#include <windows.h>
 
-int main(int argc, char* argv[]) {
-  return EXIT_SUCCESS;
+BOOL WINAPI DllMain(HINSTANCE hinstance, DWORD reason, LPVOID reserved) {
+  return TRUE;
 }