Make last Tramp change backward compatible to Emacs 24

* lisp/net/tramp-cache.el (tramp-get-file-property):
* lisp/net/tramp-sh.el (tramp-maybe-open-connection):
* lisp/net/tramp-smb.el (tramp-smb-maybe-open-connection):
Make them backward compatible to Emacs 24.
2 jobs for master in 55 minutes and 59 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #886
test-all

00:55:59

passed #887
test-filenotify-gio

00:41:37