Move GDR status out of PicHeader structure into Picture

source/Lib/CommonLib/CodingStructure.cpp

source/Lib/CommonLib/CodingStructure.h

source/Lib/CommonLib/ContextModelling.cpp

source/Lib/CommonLib/InterPrediction.cpp

source/Lib/CommonLib/Picture.cpp

source/Lib/CommonLib/Picture.h

source/Lib/CommonLib/Slice.h

source/Lib/CommonLib/UnitTools.cpp

source/Lib/DecoderLib/DecLib.cpp

source/Lib/DecoderLib/DecLib.h

source/Lib/DecoderLib/VLCReader.cpp

source/Lib/DecoderLib/VLCReader.h

source/Lib/EncoderLib/EncCu.cpp

source/Lib/EncoderLib/EncGOP.cpp

source/Lib/EncoderLib/EncSlice.cpp

source/Lib/EncoderLib/InterSearch.cpp

source/Lib/EncoderLib/IntraSearch.cpp

source/Lib/EncoderLib/VLCWriter.cpp