Change the header file name into lower case so it can work on GNU/Linux for MinGW cross-compiling. (#144)
diff --git a/portable/MSVC-MingW/portmacro.h b/portable/MSVC-MingW/portmacro.h
index 83b13b1..3812878 100644
--- a/portable/MSVC-MingW/portmacro.h
+++ b/portable/MSVC-MingW/portmacro.h
@@ -28,8 +28,8 @@
#ifndef PORTMACRO_H
#define PORTMACRO_H
-#include <Windows.h>
-#include <WinBase.h>
+#include <windows.h>
+#include <winbase.h>
/******************************************************************************
Defines