force flush of command lists & GPU sync when doing non-partial replay
force flush of command lists & GPU sync when doing non-partial replay

* In some cases there was an unpredictable crash when starting a replay
  loop, doing a full frame replay immediately after a previous replay.
  There were no debug messages, and the debug layer fixed it - as did
  enabling single flush validate. It seems to me some timing/overloading
  issue, and doing this sync should be relatively harmless so we use
  this to avoid the crash.

etnlGD/renderdoc,cgmb/renderdoc,michaelrgb/renderdoc,TurtleRockStudios/renderdoc_public,baldurk/renderdoc,Zorro666/renderdoc,googlestadia/renderdoc,TurtleRockStudios/renderdoc_public,Zorro666/renderdoc,etnlGD/renderdoc,cgmb/renderdoc,googlestadia/renderdoc,googlestadia/renderdoc,etnlGD/renderdoc,Zorro666/renderdoc,etnlGD/renderdoc,michaelrgb/renderdoc,michaelrgb/renderdoc,baldurk/renderdoc,googlestadia/renderdoc,etnlGD/renderdoc,baldurk/renderdoc,Zorro666/renderdoc,cgmb/renderdoc,TurtleRockStudios/renderdoc_public,michaelrgb/renderdoc,cgmb/renderdoc,TurtleRockStudios/renderdoc_public,Zorro666/renderdoc,googlestadia/renderdoc,etnlGD/renderdoc,baldurk/renderdoc,Zorro666/renderdoc,TurtleRockStudios/renderdoc_public,googlestadia/renderdoc,TurtleRockStudios/renderdoc_public,michaelrgb/renderdoc,baldurk/renderdoc,baldurk/renderdoc,cgmb/renderdoc