fix picHeader::maxMTTHierarchyDepth not being initialized. picHeader::maxMTTHierarchyDepth is inherited from reused pic with possibly a wrong value if SplitConsOverrideFlag is set to ON by the m_uiNumBlk stuff and not maxMTTHierarchyDepthByTid. Configurations where maxMTTHierarchyDepthByTid have some values equal to maxMTTHierarchyDepth have incorrect results.