tests/filtergraphs/scalenorm

sws_flags=+accurate_rnd+bitexact;
testsrc=s=128x96  : d=1:r=5, format=yuv420p [a];
testsrc=s=160x120 : d=1:r=5                 [b];
[a][b] concat=unsafe=1, scale=flags=+accurate_rnd+bitexact