avformat/aadec: Check for scanf() failure

Fixes: use of uninitialized variables
Fixes: blank.aa

Found-by: Chamal De Silva <chamal.desilva@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
static int get_second_size(char *codec_name)
{
    int result = -1;

    if (!strcmp(codec_name, "mp332")) {
        result = 3982;
    } else if (!strcmp(codec_name, "acelp16")) {
        result = 2000;
    } else if (!strcmp(codec_name, "acelp85")) {
        result = 1045;
    }

    return result;
}

static int get_second_size(char *codec_name)
{
    int result = -1;

    if (!strcmp(codec_name, "mp332")) {
        result = 3982;
    } else if (!strcmp(codec_name, "acelp16")) {
        result = 2000;
    } else if (!strcmp(codec_name, "acelp85")) {
        result = 1045;
    }

    return result;
}
