Use defined macros and define intermediate variables to avoid code
repetition.

m_decodingUnitDpbDuParamsInPicTimingSeiFlag was not copied

As in specification: "The value of pt_sublayer_delays_present_flag[ bp_max_sublayers_minus1 ] is inferred to be equal to 1"

Currently m_latestDRAPPOC for pictures which follow DRAP is always MAX_INT.

This prevents checkConformanceForDRAP() from checking active ref pic constraints

When reading SEI NAL unit of size=0 (eg. DRAP SEI)
vector `buf` may happen to be empty.

In this case expression `&buf[0]` causes undefined behavior.

It seems that caller of activateAPS() expects that pointers to lmcsAPS and scalingListAPS are updated.

However they are not and then checkParameterSetsInclusionSEIconstraints() does not perform proper checks for LMCS and ScalingList APSs