wlc.h: Null is allowed to add_fd arg
wlc.h: Null is allowed to add_fd arg

ammen99/wlc,ss1h2a3tw/wlc,scarabeusiv/wlc,ss1h2a3tw/wlc,yohanesu75/wlc,vially/wlc,gpyh/wlc,Cloudef/wlc,Cloudef/wlc,scarabeusiv/wlc,Earnestly/wlc,Earnestly/wlc,yohanesu75/wlc,Enerccio/ewlc,Enerccio/ewlc,ammen99/wlc,gpyh/wlc,vially/wlc