JVET-P0116: For independent layers, use POC MSB cycle signalling

For independent layers, use POC MSB cycle signalling. In the SPS, there is a flag to control whether picture header has ph_poc_msb_cycle_present_flag, and a length in the SPS. When ph_poc_msb_cycle_present_flag is equal to 1, the POC MSB cycle, u(v) coded, is signalled in the picture header. When POC MSB cycle is present, the POC MSB of the picture is set to poc_msb_cycle * MaxPicOrderCntLsb.