Updating trybot root location in codereview.settings.
Updating trybot root location in codereview.settings.

This is needed due to changes in the way the trybots checkout the source code before applying the uploaded patch for a try job.

BUG=none
TEST=local master and submitted tryjob + verifying update step succeeded. Tryjob submitted to live try master with patch applying properly for all bots.
Review URL: https://webrtc-codereview.appspot.com/1059004
chucvv/libyuv,Vairn/libyuv,hyper123/libyuv,ganzhijie/libyuv,bingerZhang/libyuv,OrenHg/libyuv,sathishkumars3/libyuv,alfahim/libyuv,fate-extra/libyuv,Vairn/libyuv,fate-extra/libyuv,syoshimu/libyuv,skufog/libyuv,RockySteveJobs/libyuv,sathishkumars3/libyuv,dilagurung/libyuv,mosterta/libyuv,skufog/libyuv,yzhikan/libyuv,alfahim/libyuv,hajunho/libyuv,wl-chuang/libyuv,hajunho/libyuv,bingerZhang/libyuv,OrenHg/libyuv,RockySteveJobs/libyuv,gigakuma/libyuv,uditkumawat/libyuv,alfahim/libyuv,OrenHg/libyuv,wl-chuang/libyuv,StopProducing/libyuv,bingerZhang/libyuv,ganzhijie/libyuv,aberejohn/libyuv,dexcz/libyuv,skufog/libyuv,VladDrake/libyuv,dilagurung/libyuv,uditkumawat/libyuv,KerwinMa/libyuv,KerwinMa/libyuv,chucvv/libyuv,sathishkumars3/libyuv,WangYongHai/libyuv,uraran/libyuv,aberejohn/libyuv,hyper123/libyuv,mosterta/libyuv,VladDrake/libyuv,dexcz/libyuv,hyper123/libyuv,mosterta/libyuv,StopProducing/libyuv,fate-extra/libyuv,yzhikan/libyuv,dexcz/libyuv,WangYongHai/libyuv,syoshimu/libyuv,gigakuma/libyuv,VladDrake/libyuv,dilagurung/libyuv,RockySteveJobs/libyuv,aberejohn/libyuv,wl-chuang/libyuv,gigakuma/libyuv,yzhikan/libyuv,Vairn/libyuv,uraran/libyuv,StopProducing/libyuv,uditkumawat/libyuv,ganzhijie/libyuv,hajunho/libyuv,uraran/libyuv,syoshimu/libyuv,KerwinMa/libyuv,WangYongHai/libyuv,chucvv/libyuv