Ah! I finally have a progress bar that doesn't stall the build!
- pipe size in Linux is only 8*512=4096 bytes
- pipe size is not setable
- when the feeding process spits out data faster than the eating
process can read it, then the feeding process stalls after 4KiB
of data sent to the pipe
- for us, the progress bar would spawn a sub-shell every line,
and the sub-shell would in turn spawn a 'date' command.
Which was sloooww as hell, and would cause some kind of a
starvation: the pipe was full most of the time, and the
feeding process was stalled all this time.

Now, we use internal variables and a little hack based onan offset
to determine the elapsed time. Much faster this way, but still
CPU-intensive.

 2004-10-24  Daniel Jacobowitz  <dan@debian.org>

 	* opncls.c (bfd_close): Return TRUE for BFD_IN_MEMORY.

 Index: src/bfd/opncls.c

 ===================================================================

 RCS file: /big/fsf/rsync/src-cvs/src/bfd/opncls.c,v

 retrieving revision 1.25

 diff -u -p -r1.25 opncls.c

 --- src/bfd/opncls.c	10 Oct 2004 13:58:05 -0000	1.25

 +++ src/bfd/opncls.c	24 Oct 2004 17:52:53 -0000

 @@ -598,7 +598,7 @@ bfd_close (bfd *abfd)

    if (!(abfd->flags & BFD_IN_MEMORY))

      ret = abfd->iovec->bclose (abfd);

    else

 -    ret = 0;

 +    ret = TRUE;

    /* If the file was open for writing and is now executable,

       make it so.  */