make action_dependencies test win32 and c89 friendly

test/ninja/action_dependencies/src/b.c

-/* Copyright (c) 2011 Google Inc. All rights reserved.
+/* Copyright (c) 2012 Google Inc. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include <stdio.h>
 
 #include "b.h"
 
 int main(int argc, char** argv) {
+  FILE* f;
   if (argc < 2)
     return 1;
-  FILE* f = fopen(argv[1], "wt");
+  f = fopen(argv[1], "wt");
   fprintf(f, "#define VALUE %d\n", funcA());
   fclose(f);
   return 0;
 }