Drop remaining unneeded != NULL

cmdutils.c

ffmpeg.c

ffplay.c

ffserver.c

libavcodec/libx264.c

libavcodec/mpegaudiodec_template.c

libavcodec/parser.c

libavfilter/af_amix.c

libavfilter/libmpcodecs/vf_eq2.c

libavformat/lrcenc.c

libavformat/matroskadec.c

libavformat/mov.c

libavformat/rtpdec_h264.c

libavformat/sctp.c

libavformat/webmdashenc.c

libpostproc/postprocess.c