- nalu_data points to the beginning of the nalu, instead of
beginning of the slice header which excluded the nalu
header.
- nalu_size is the size of the whole nalu.
- header_bit_size calculation is corrected. The size used to exclude
emulation prevention bytes.
Change-Id: Ic00f42caeddf7b4701f3948e6ef8a3537fd7f770