server: Added data_size_t type to represent sizes in the server protocol.

Make it an unsigned int to save some space on Win64, if we need to
transfer more than 4Gb over the server pipe something is seriously
wrong.
diff --git a/server/object.h b/server/object.h
index 57dab07..46b34e1 100644
--- a/server/object.h
+++ b/server/object.h
@@ -50,7 +50,7 @@
 struct unicode_str
 {
     const WCHAR *str;
-    size_t       len;
+    data_size_t  len;
 };
 
 /* operations valid on all objects */
@@ -103,7 +103,7 @@
 extern void *mem_alloc( size_t size );  /* malloc wrapper */
 extern void *memdup( const void *data, size_t len );
 extern void *alloc_object( const struct object_ops *ops );
-extern const WCHAR *get_object_name( struct object *obj, size_t *len );
+extern const WCHAR *get_object_name( struct object *obj, data_size_t *len );
 extern void dump_object_name( struct object *obj );
 extern void *create_object( struct namespace *namespace, const struct object_ops *ops,
                             const struct unicode_str *name, struct object *parent );
@@ -179,8 +179,8 @@
 
 /* atom functions */
 
-extern atom_t add_global_atom( struct winstation *winstation, const WCHAR *str, size_t len );
-extern atom_t find_global_atom( struct winstation *winstation, const WCHAR *str, size_t len );
+extern atom_t add_global_atom( struct winstation *winstation, const WCHAR *str, data_size_t len );
+extern atom_t find_global_atom( struct winstation *winstation, const WCHAR *str, data_size_t len );
 extern int grab_global_atom( struct winstation *winstation, atom_t atom );
 extern void release_global_atom( struct winstation *winstation, atom_t atom );