Function mp3_requantize 

pub fn mp3_requantize(
    is_val: i32,
    global_gain: u16,
    scalefac: u8,
    scalefac_scale: bool,
    subblock_gain: u8,
    preflag: bool,
    _sfb_index: usize,
) -> i32

Requantize a decoded Huffman value using integer arithmetic

Approximates: xr = sign(is) * |is|^(4/3) * 2^((global_gain - 210) / 4)