some PSNR/bitrate gain if adaptive quant is used
initalize qscale_table correctly (it was pretty much random since the qp->lambda change)
  this probably has not much effect as the table isnt used currently IIRC


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@7342 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b