ws_snd1: Fix wrong samples counts.

This makes the check that avoids overwrite of the samples array actually
work properly.

fixes CVE-2012-0848
CC: libav-stable@libav.org

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Justin Ruggles <justin.ruggles@gmail.com>
