stats: fix incorrect fraction calculation (what was I thinking?)

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
log: define DBG_STATS for stats debug output

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
stats: create a callback API for reporting bitrates & statistics

use command line argument '-b' to enable bitrate & statistics display

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>