dts: Remove redundant 'if' for freeing.
dts: Evaluate return value properly.
h264: Evaluate return value properly.
hevc: Evaluate return value properly.
nalu: Evaluate return value of lsmash_add_entry() properly.
mp4a: Remove redundant 'if's for freeing.
mp4a: Evaluate return value properly.
mp4sys: Remove redundant 'if' for freeing.
mp4sys: Evaluate return value properly.
vc1: Remove redundant 'if's for freeing.
vc1: Evaluate return value properly.
description: Remove redundant 'if' for freeing.
mp4sys: Evaluate return value properly.