optimize: rewrite TComTrQuant::xGetCodedLevel

--HG--
extra : amend_source : b7cd4e3bb25dbf5cec137b96508e6feff53cda8d
replace parameters (oneCtx, absCtx) by pointer m_estBitsSbac->..
use mask operator to avoid branch
vbv: fix race condition in processRowEncoder, store row qp directly in m_pic->m_rowDiagQp.

--HG--
branch : stable
Merge with stable
TComTrQuant: nits (no change)