SystemTools: Move typedef mode_t inside the SystemTools class

Cleans up a smidge of global namespace pollution. Allows using this
header file in the same compilation unit with other header files
that may also contain a mode_t typedef, possibly with a different
underlying type.

Actually encountered in the wild when trying to compile a class that
uses both log4cpp and VTK.

Change-Id: Iba5592778fc21d66946026847537d914e56f332b

SystemTools.hxx.in

@@ -42,10 +42,6 @@ namespace @KWSYS_NAMESPACE@
 }
 #endif // va_list
 
-#if defined( _MSC_VER )
-typedef unsigned short mode_t;
-#endif
-
 /* Define these macros temporarily to keep the code readable.  */
 #if !defined (KWSYS_NAMESPACE) && !@KWSYS_NAMESPACE@_NAME_IS_KWSYS
 # define kwsys_stl @KWSYS_NAMESPACE@_stl
@@ -684,6 +680,10 @@ public:
    */
   static long int CreationTime(const char* filename);
 
+  #if defined( _MSC_VER )
+  typedef unsigned short mode_t;
+  #endif
+
   /**
    * Get and set permissions of the file.
    */