sysprep: allow to specify globbing for --delete

Adapt the globbing part from the old --remote-path work previously
proposed for sysprep [1], allowing --delete to perform globbing when
deleting paths.

[1] https://www.redhat.com/archives/libguestfs/2013-October/msg00045.html

sysprep/sysprep_operation_delete.ml

@@ -27,7 +27,9 @@ let add_paths path = paths := path :: !paths
 
 let path_perform g root =
   let paths = List.rev !paths in
-  List.iter g#rm_rf paths;
+  if paths <> [] then (
+    List.iter (fun glob -> Array.iter g#rm_rf (g#glob_expand glob)) paths
+  );
   []
 
 let op = {