hevc: simplify SAO computation, delay from one row its computation
(cherry picked from commit f2c5f647cec786df26f442a85e6d685a131a50c9)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
hevc: move restore_tqb where it should be.
(cherry picked from commit 8fafc96a9805d11bfe32537c8f78a294a5844065)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
hevc: use local variable for split_cu_flag
(cherry picked from commit ee71e9e9c12fc47856c452efb278f9f593a923ee)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>