avcodec/apedec: Fix integer overflow

Fixes: out of array access
Fixes: PoC.ape and others

Found-by: Bingchang, Liu@VARAS of IIE
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
static void entropy_decode_mono_0000(APEContext *ctx, int blockstodecode)
{
    decode_array_0000(ctx, &ctx->gb, ctx->decoded[0], &ctx->riceY,
                      blockstodecode);
}

static void entropy_decode_mono_0000(APEContext *ctx, int blockstodecode)
{
    decode_array_0000(ctx, &ctx->gb, ctx->decoded[0], &ctx->riceY,
                      blockstodecode);
}
