all games: Fix a case of dynamic shadows bleeding through thin surfaces#1686

copperpixel wants to merge 2 commits intoValveSoftware:masterValveSoftware/source-sdk-2013:masterfrom

copperpixel:rttshadow_clipping_fixcopperpixel/source-sdk-2013:rttshadow_clipping_fixCopy head branch name to clipboard