Some fixes for build with MinGW

git-svn-id: https://assimp.svn.sourceforge.net/svnroot/assimp/trunk@12 67173fc5-114c-0410-ac8e-9d2fd5bffc1f

code/Win32DebugLogStream.h

@@ -3,13 +3,15 @@
 
 #include "LogStream.h"
 
-#ifdef _MSC_VER
+//#ifdef _MSC_VER
+#ifdef WIN32
 #include "Windows.h"
 #endif
 
 namespace Assimp
 {
-#ifdef _MSC_VER
+//#ifdef _MSC_VER
+#ifdef WIN32
 
 // ---------------------------------------------------------------------------
 /**	@class	Win32DebugLogStream