Convert output messages in merge-recursive to past tense.

Convert output messages in merge-recursive to past tense.

Now that we are showing the output messages for verbosity levels
<5 after all actions have been performed (due to the progress meter
running during the actions) it can be confusing to see messages in
the present tense when the user is looking at a '100% done' message
right above them.  Converting the messages to past tense will appear
more correct in this case, and shouldn't affect a developer who is
debugging the application and running it at a verbosity level >=5.

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