Use lowercase windows.h in includes to fix Windows cross compilation using mingw.

bench/BenchSysTimer_windows.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "BenchSysTimer_windows.h"
 
 //Time
 #define WIN32_LEAN_AND_MEAN 1
-#include <Windows.h>
+#include <windows.h>
 
 static ULONGLONG winCpuTime() {
     FILETIME createTime;
     FILETIME exitTime;
     FILETIME usrTime;
     FILETIME sysTime;
     if (0 == GetProcessTimes(GetCurrentProcess()
                            , &createTime, &exitTime
                            , &sysTime, &usrTime))
     {
@@ skipping 32 matching lines @@
 
     LARGE_INTEGER frequency;
     if (0 == ::QueryPerformanceFrequency(&frequency)) {
         return 0.0L;
     } else {
         return static_cast<double>(ticks_elapsed.QuadPart)
              / static_cast<double>(frequency.QuadPart)
              * 1000.0L;
     }
 }