Stop flooding log files while waiting for TNG

[Alessio Vanni]

Hello,

currently "gnunet-service-transport" logs the time it took to send some
bytes to a certain peer.  The problem with this logging is that it
floods the logfile with a lot of essentially useless informations.

Aside not really telling anything useful to users (the timing is really
interesting only to those people measuring the performance of the
service/network), it generates a lot of disk writing and easily fill up
disk space (after something like 30 minutes of my peer being active, I
get a log file of several megabytes.)

Another downside is that it actually hides other informations that might
actually be important: for example right now I'm getting a lot of
protocol violation messages within CADET; they were hidden by transport
before (or anyway hard to find.)

The attached patch adds an option to configure.ac to control the
logging. It's disabled by default so normal users don't have to change
their "configure" incantation and people actually interested in
transport performance can opt-in without too much hassle (the option
name is long on purpose.)

When TNG is ready to take over, the option can be removed or even
recycled for the new code. In the meantime, it will avoid a lot of noise
and disk activity.

Thanks,
A.V.

0001-Disable-some-diagnostic-until-TNG-is-available.patch
Description: Patch for GNUnet