cus-dep fix for build failure first occurring with 2011-06-13T08:21:09Z!rudalics...

cus-dep fix for build failure first occurring with 2011-06-13T08:21:09Z!rudalics@gmx.at

The symptom was `make custom-dep' failing with "Unknown terminal type".
This is caused by `display-buffer' trying to pop-up a frame in batch mode.
I think this cus-dep change may be just papering over the immediate
manifestation of the underlying problem.

* lisp/cus-dep.el (custom-make-dependencies): Use up command-line-args-left.