There are a couple of loops identified here that output a lot of
tracing each iteration for little value. Make them only trace at
higher levels (-x -x and above).
Points of actual interest within the loops are replaced with an
explicit "echo" statement.
Additionally, export DIB_DEBUG_TRACE explicitly and in all cases, not
just when tracing is turned on.
Change-Id: Id710c0b111fc1f5e1ae87fc35f6db28b24867bad