Tidy up uses of Windows.h by adding WindowsWrapper.hpp

This header brings in the Win32 API header, with some small modifications
applied to prevent clashes with our code. This means those modifications
don't need to be made in each place that we bring in Windows.h

Change-Id: Ie817c7a167eccbe1ac6a49d3fc940eef8b2f534d
Signed-off-by: Robert Hughes <robert.hughes@arm.com>
diff --git a/src/armnnUtils/Filesystem.cpp b/src/armnnUtils/Filesystem.cpp
index 6c8175b..886d7da 100644
--- a/src/armnnUtils/Filesystem.cpp
+++ b/src/armnnUtils/Filesystem.cpp
@@ -9,8 +9,7 @@
 #include <sys/stat.h>
 #include <stdio.h>
 #elif defined(_MSC_VER)
-#define WIN32_LEAN_AND_MEAN
-#include <Windows.h>
+#include "WindowsWrapper.hpp"
 #endif
 
 namespace armnnUtils