stage1/diagexec: support comma-separated list of gids w/setgroups()
stage1/diagexec: support comma-separated list of gids w/setgroups()

s-urbaniak/rkt,jakon89/rkt,markllama/rkt,kinvolk/rkt,cab105/rkt,alban/rkt,mike1729/rkt,Shashwatsh/rkt,liubq919/rkt,yifan-gu/rocket,krnowak/rkt,alban/rkt,matthaias/rkt,Shashwatsh/rkt,yifan-gu/rocket,jasonchaffee/rkt,jjlakis/rkt,matthaias/rkt,lucasallan/rkt,rkt/rkt,endocode/rkt,markllama/rkt,jonboulle/rkt,iaguis/rkt,Shashwatsh/rkt,sgotti/rkt,jzelinskie/rkt,tmrts/rkt,coreos/rkt,euank/rkt,il9ue/rkt,endocode/rkt,linki/rkt,iaguis/rkt,achanda/rkt,achanda/rkt,jjlakis/rkt,dgonyeo/rkt,sinfomicien/rkt,nhlfr/rkt,adfernandes/rkt,rkt/rkt,shobhit85/rkt,mike1729/rkt,joshix/rkt,dgonyeo/rkt,intelsdi-x/rkt,intelsdi-x/rkt,kinvolk/rkt,jjlakis/rkt,euank/rkt,kbrwn/rkt,adfernandes/rkt,squeed/rkt,akshaykarle/rkt,sinfomicien/rkt,kinvolk/rkt,ybubnov/rkt,jonboulle/rkt,jakon89/rkt,liubq919/rkt,nhlfr/rkt,jonboulle/rkt,nhlfr/rkt,liugenping/rkt,jasonchaffee/rkt,mike1729/rkt,monstermunchkin/rkt,iaguis/rkt,liugenping/rkt,Wilybald/rkt,blixtra/rkt,sinfomicien/rkt,rkt/rkt,lucasallan/rkt,endocode/rkt,dgonyeo/rkt,ybubnov/rkt,cab105/rkt,kbrwn/rkt,sgotti/rkt,blixtra/rkt,tmrts/rkt,jzelinskie/rkt,ybubnov/rkt,Wilybald/rkt,sstabellini/rkt,monstermunchkin/rkt,coreos/rkt,joshix/rkt,matthaias/rkt,linki/rkt,jasonchaffee/rkt,s-urbaniak/rkt,il9ue/rkt,joshix/rkt,kbrwn/rkt,alban/rkt,coreos/rkt,akshaykarle/rkt,jzelinskie/rkt,shobhit85/rkt,liubq919/rkt,kinvolk/rkt,s-urbaniak/rkt,shobhit85/rkt,lucasallan/rkt,monstermunchkin/rkt,Wilybald/rkt,squeed/rkt,sstabellini/rkt,yifan-gu/rkt,akshaykarle/rkt,intelsdi-x/rkt,krnowak/rkt,tmrts/rkt,jakon89/rkt,achanda/rkt,cab105/rkt,Wilybald/rkt,yifan-gu/rkt,sstabellini/rkt,yifan-gu/rkt,rkt/rkt,joshix/rkt,sgotti/rkt,lucasallan/rkt,krnowak/rkt,il9ue/rkt,linki/rkt,euank/rkt,blixtra/rkt,markllama/rkt,adfernandes/rkt,yifan-gu/rocket,liugenping/rkt,squeed/rkt