swresample/swresample: fix sample drop loop end condition

Fixes Ticket3985

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit f9fefa499f0af48f47ea73c8ce0b25df0976c315)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
1 file changed