pcmdec: consistently use codec_id, fixes out of array reads

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/pcm.c

@@ -211,7 +211,7 @@ static av_cold int pcm_decode_init(AVCodecContext *avctx)
         return AVERROR(EINVAL);
     }
 
-    switch (avctx->codec->id) {
+    switch (avctx->codec_id) {
     case AV_CODEC_ID_PCM_ALAW:
         for (i = 0; i < 256; i++)
             s->table[i] = alaw2linear(i);
@@ -227,7 +227,7 @@ static av_cold int pcm_decode_init(AVCodecContext *avctx)
     avctx->sample_fmt = avctx->codec->sample_fmts[0];
 
     if (avctx->sample_fmt == AV_SAMPLE_FMT_S32)
-        avctx->bits_per_raw_sample = av_get_bits_per_sample(avctx->codec->id);
+        avctx->bits_per_raw_sample = av_get_bits_per_sample(avctx->codec_id);
 
     avcodec_get_frame_defaults(&s->frame);
     avctx->coded_frame = &s->frame;
@@ -315,7 +315,7 @@ static int pcm_decode_frame(AVCodecContext *avctx, void *data,
     }
     samples = s->frame.data[0];
 
-    switch (avctx->codec->id) {
+    switch (avctx->codec_id) {
     case AV_CODEC_ID_PCM_U32LE:
         DECODE(32, le32, src, samples, n, 0, 0x80000000)
         break;