transport: pass summary_width down the callchain

transport: pass summary_width down the callchain

The callchain that originates at transport_print_push_status()
eventually hits a single leaf function, print_ref_status(), that is
used to show from what old object to what new object a ref got
updated, and the width of the part that shows old and new object
names used a constant TRANSPORT_SUMMARY_WIDTH.

Teach the callchain to pass the width down from the top instead.
This allows a future enhancement to compute the necessary display
width before calling down this callchain.

Signed-off-by: Junio C Hamano <gitster@pobox.com>