Also makes sure that the percentage output from the verbose and
non-verbose modes of timer_test are the same and print a cumulative
accuracy which smooths out the jitter for each pass.

If the time it takes to read in 1 second worth of data is longer than 1
second  accuracy will be 0%.

(closes issue #18573)
Reported by: smurfix

Signed-off-by: Shaun Ruffell <sruffell@digium.com>

git-svn-id: http://svn.astersk.org/svn/dahdi/tools/trunk@10216 17933a7a-c749-41c5-a318-cba88f637d49