Besides simplifying address computations (it saves 432B of .text
in hevcdsp.o alone here) it also fixes undefined behaviour that
occurs if mx or my are 0 (happens when the filters are unused)
because they lead to an array index of -1 in the old code.
This happens in the checkasm-hevc_pel FATE-test.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Reviewed-by: Nuo Mi <nuomi2021@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>