BUG/MINOR: log: Dump good %B and %U values in logs

BUG/MINOR: log: Dump good %B and %U values in logs

When per-stream "bytes_in" and "bytes_out" counters where replaced in 3.3,
the wrong counters were used for %B and %U values in logs. In the
configuration manual and the commit message, it was specificed that
"bytes_in" was replaced by "req_in" and "bytes_out" by "res_in", but in the
code, wrong counters were used. It is now fixed.

This patch should fix the issue #3208. It must be backported to 3.3.