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

While it doesn't matter on Windows, mingw on case-sensitive OSes uses all lower case filenames for platform include files. I found the problem in SkCondVar.h from Mozilla checkout of skia sources, but the patch contains a fix for the whole skia tree.

R=bungeman@google.com

Review URL: https://codereview.chromium.org/99173003

git-svn-id: http://skia.googlecode.com/svn/trunk@12461 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/utils/win/SkAutoCoInitialize.cpp b/src/utils/win/SkAutoCoInitialize.cpp
index dd6e936..89115bf 100644
--- a/src/utils/win/SkAutoCoInitialize.cpp
+++ b/src/utils/win/SkAutoCoInitialize.cpp
@@ -8,7 +8,7 @@
 
 
 #define WIN32_LEAN_AND_MEAN
-#include <Windows.h>
+#include <windows.h>
 #include <ole2.h>
 #include "SkAutoCoInitialize.h"