Kill the useless progress meter in merge-recursive

Kill the useless progress meter in merge-recursive

The mess known as the progress meter in merge-recursive was my own
fault; I put it in thinking that we might be spending a lot of time
resolving unmerged entries in the index that were not handled by
the simple 3-way index merge code.

Turns out we don't really spend that much time there, so the progress
meter was pretty much always jumping to "(n/n) 100%" as soon as
the program started.  That isn't a very good indication of progress.

Since I don't have a great solution for how a progress meter should
work here, I'm proposing we back it out entirely.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>