avformat/mov: Fix DoS in read_tfra()

Fixes: Missing EOF check in loop
No testcase

Found-by: Xiaohei and Wangchu from Alibaba Security Team
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
static uint32_t yuv_to_rgba(uint32_t ycbcr)
{
    uint8_t r, g, b;
    int y, cb, cr;

    y  = (ycbcr >> 16) & 0xFF;
    cr = (ycbcr >> 8)  & 0xFF;
    cb =  ycbcr        & 0xFF;

    b = av_clip_uint8((1164 * (y - 16)                     + 2018 * (cb - 128)) / 1000);
    g = av_clip_uint8((1164 * (y - 16) -  813 * (cr - 128) -  391 * (cb - 128)) / 1000);
    r = av_clip_uint8((1164 * (y - 16) + 1596 * (cr - 128)                    ) / 1000);

    return (r << 16) | (g << 8) | b;
}

static uint32_t yuv_to_rgba(uint32_t ycbcr)
{
    uint8_t r, g, b;
    int y, cb, cr;

    y  = (ycbcr >> 16) & 0xFF;
    cr = (ycbcr >> 8)  & 0xFF;
    cb =  ycbcr        & 0xFF;

    b = av_clip_uint8((1164 * (y - 16)                     + 2018 * (cb - 128)) / 1000);
    g = av_clip_uint8((1164 * (y - 16) -  813 * (cr - 128) -  391 * (cb - 128)) / 1000);
    r = av_clip_uint8((1164 * (y - 16) + 1596 * (cr - 128)                    ) / 1000);

    return (r << 16) | (g << 8) | b;
}
