analysis: remove PartSize argument to checkIntraInInter_rd0_4
analysis: remove bMergeOnly argument to checkInter_rd0_4, always false
analysis: initialize job counters
analysis: use source buffer for source stride

it was always a coincidence that the output stride matched
analysis: nit, remove obviously wrong comment
analysis: further work on parallel ME
fix bug in 73c6c9086577 for rdLevel=0
rc : correct max AU size for first frame
rc: correct the threshold for resetABR function
analysis: remove unused variables, fixes warnings
search: make some helper methods const
search: use sad cost directly to pick MVP

there's no point in use SAD RD cost if all the candidates have the same
estimated bit cost.
search: remove redundant calls to prepMotionCompensation()
encoder: correct logging of number of WPP streams