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.

 --- gdb-6.1.1-dist/readline/configure	2003-05-27 18:29:47.000000000 -0500

 +++ gdb-6.1.1/readline/configure	2004-08-09 14:20:23.000000000 -0500

 @@ -6249,7 +6249,12 @@

  echo "$as_me:$LINENO: checking for mbstate_t" >&5

 +echo $ECHO_N "bash_cv_have_mbstate_t=$bash_cv_have_mbstate_t" >&6

  echo $ECHO_N "checking for mbstate_t... $ECHO_C" >&6

 +if test "${bash_cv_have_mbstate_t+set}" != set; then

 +  bash_cv_have_mbstate_t=yes

 +  echo $ECHO_N "WARNING!! forcing to yes!!! $ECHO_C" >&6

 +fi

  if test "${bash_cv_have_mbstate_t+set}" = set; then

    echo $ECHO_N "(cached) $ECHO_C" >&6

  else