[MERGE] Extend -Dhpss to emit a count of HPSS calls to stderr

[Martin Pool]

Martin Pool has voted tweak.
Status is now: Conditionally approved
Comment:
It would be nice, in a later patch, to also get the count of bytes sent 
and received.  That may be a bit complex for calls that stream the 
request and response data.

It would be nice to have a proper repr too.

For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C20080925074701.GA19903%40steerpike.home.puzzling.org%3E
Project: Bazaar