Mark some arrays that never change as const.

configure

libavcodec/aaccoder.c

libavcodec/aacenc.c

libavcodec/aacenc.h

libavcodec/aic.c

libavcodec/amrnbdata.h

libavcodec/amrwbdata.h

libavcodec/atrac3plus.c

libavcodec/dfa.c

libavcodec/g722dec.c

libavcodec/h263data.c

libavcodec/h263data.h

libavcodec/indeo3.c

libavcodec/indeo4data.h

libavcodec/mpeg4videodec.c

libavcodec/on2avc.c

libavcodec/on2avcdata.c

libavcodec/on2avcdata.h

libavcodec/opus_silk.c

libavcodec/qsvdec_h2645.c