Fixing compiler warnings:

* BLI_arithb.h - isnan definition is only needed for MSVC, but gcc/mingw complains about it

* file-selectors - moved BLI_storage_types.h or sys/stat.h includes before BLI_winstuff.h includes,  to silence warnings about S_ISDIR.

source/blender/blenlib/BLI_arithb.h

@@ -55,7 +55,9 @@ extern "C" {
 #endif
 
 #ifdef WIN32
-    #define isnan(n) _isnan(n)
+	#ifndef FREE_WINDOWS
+		#define isnan(n) _isnan(n)
+	#endif
 #endif
 
 #define MAT4_UNITY {{ 1.0, 0.0, 0.0, 0.0},\

source/blender/src/drawimasel.c

@@ -51,10 +51,11 @@
 #include "DNA_material_types.h"
 
 #include "BLI_blenlib.h"
+#include "BLI_storage_types.h"
 #ifdef WIN32
 #include "BLI_winstuff.h"
 #endif
-#include "BLI_storage_types.h"
+
 
 #include "BKE_global.h"
 #include "BKE_library.h"

source/blender/src/filesel.c

@@ -34,6 +34,12 @@
 #include <string.h>
 #include <math.h>
 
+#include <sys/stat.h>
+#include <sys/types.h>
+#include "MEM_guardedalloc.h"
+
+#include "BMF_Api.h"
+
 #ifdef WIN32
 #include <io.h>
 #include <direct.h>
@@ -43,12 +49,6 @@
 #include <sys/times.h>
 #endif   
 
-#include <sys/stat.h>
-#include <sys/types.h>
-#include "MEM_guardedalloc.h"
-
-#include "BMF_Api.h"
-
 #include "BLI_blenlib.h"
 #include "BLI_arithb.h"
 #include "BLI_linklist.h"