0026381: OSD_File - close file on destruction

Add destructor for OSD_File, that unlocks and close file.

Remove senseless checks from status functions in code for Linux.

Destructor of OSD_FileNode is made protected to avoid possibility of deleting descendants by pointer to base class

src/OSD/OSD_File.hxx

@@ -52,6 +52,9 @@ public:
   
   //! Instantiates the object file, storing its name
   Standard_EXPORT OSD_File(const OSD_Path& Name);
+
+  //! Unlocks and closes a file, deletes a descriptor and destructs a file object.
+  Standard_EXPORT ~OSD_File();
   
   //! CREATES a file if it doesn't already exists or empties
   //! an existing file.