pg_basebackup and wal streaming

Better late than never (or?), here's the final cleanup of
pg_streamrecv for moving into the main distribution, per discussion
back in late dec or early jan. It also includes the "stream logs in
parallel to backup" part that was not completed on pg_basebackup.

Other than that, the only changes to pg_basebackup are the moving of a
couple of functions into streamutil.c to make them usable from both,
and the progress format output fix Fujii-san mentioned recently.

Should be complete except for Win32 support (needs thread/fork thing
for the  background streaming feature. Shouldn't be too hard, and I
guess that falls on me anyway..) and the reference documentation.

And with no feedback to my question here
(http://archives.postgresql.org/pgsql-hackers/2011-02/msg00805.php), I
went with the "duplicate the macros that are needed to avoid loading
postgres.h" path.

Yes, I realize that this is far too late in the CF process really, but
I wanted to post it anyway... If it's too late to be acceptable it
should be possible to maintain this outside the main repository until
9.2, since it only changes frontend binaries. So I'm not actually
going to put it on the CF page unless someone else says that's a good
idea, to at least share the blame from Robert ;)

--
 Magnus Hagander
 Me: http://www.hagander.net/
 Work: http://www.redpill-linpro.com/