Add missing LWS_VISIBLE to libwebsocket_set_timeout()
Add missing LWS_VISIBLE to libwebsocket_set_timeout()

This aligns it with the style of all other function declarations.
lukasz-skalski/libwebsockets,ralight/libwebsockets,jmillan/libwebsockets,wenqiwooo/syslog-libwebsockets,turbulenz/libwebsockets,lukasz-skalski/libwebsockets,sanyaade-teachings/libwebsockets,tn0502/libwebsockets,jmillan/libwebsockets,DaYeSquad/libwebsockets,pankona/libwebsockets,sartura/libwebsockets,sartura/libwebsockets,pankona/libwebsockets,PureSwift/libwebsockets,sanyaade-teachings/libwebsockets,PureSwift/libwebsockets,canopy-project/libwebsockets-canopy,peeracle/libwebsockets,wenqiwooo/syslog-libwebsockets,DaYeSquad/libwebsockets,Chilledheart/libwebsockets,abligh/libwebsockets,GroundControl-Solutions/libwebsockets,sanyaade-teachings/libwebsockets,antmicro/libwebsockets,maws/libwebsockets,peeracle/libwebsockets,dumganhar/libwebsockets,peeracle/libwebsockets,gameclosure/libwebsockets,RobertoMalatesta/libwebsockets,dumganhar/libwebsockets,JoakimSoderberg/libwebsockets,DaYeSquad/libwebsockets,RobertoMalatesta/libwebsockets,GroundControl-Solutions/libwebsockets,Chilledheart/libwebsockets,IOPOINT/libwebsockets,canopy-project/libwebsockets-canopy,pombredanne/libwebsockets,SoapyMan/libwebsockets,lukasz-skalski/libwebsockets,gameclosure/libwebsockets,GroundControl-Solutions/libwebsockets,canopy-project/libwebsockets-canopy,ralight/libwebsockets,abligh/libwebsockets,antmicro/libwebsockets,kaostao/libwebsockets,pombredanne/libwebsockets,antmicro/libwebsockets,dumganhar/libwebsockets,peeracle/libwebsockets,sartura/libwebsockets,pombredanne/libwebsockets,jmillan/libwebsockets,gameclosure/libwebsockets,PureSwift/libwebsockets,cambridgehackers/libwebsockets,antmicro/libwebsockets,mushroomgithub/libwebsockets,JoakimSoderberg/libwebsockets,ralight/libwebsockets,kaostao/libwebsockets,GroundControl-Solutions/libwebsockets,giovanni-liboni/libwebsockets,sartura/libwebsockets,cambridgehackers/libwebsockets,turbulenz/libwebsockets,maws/libwebsockets,DaYeSquad/libwebsockets,RobertoMalatesta/libwebsockets,wenqiwooo/syslog-libwebsockets,SoapyMan/libwebsockets,sartura/libwebsockets,lukasz-skalski/libwebsockets,wenqiwooo/syslog-libwebsockets,mushroomgithub/libwebsockets,dumganhar/libwebsockets,sanyaade-teachings/libwebsockets,Chilledheart/libwebsockets,gameclosure/libwebsockets,sartura/libwebsockets,mushroomgithub/libwebsockets,pombredanne/libwebsockets,giovanni-liboni/libwebsockets,tn0502/libwebsockets,dumganhar/libwebsockets,PureSwift/libwebsockets,SoapyMan/libwebsockets,sartura/libwebsockets,kaostao/libwebsockets,kaostao/libwebsockets,pankona/libwebsockets,IOPOINT/libwebsockets,JoakimSoderberg/libwebsockets,DaYeSquad/libwebsockets,GroundControl-Solutions/libwebsockets,cambridgehackers/libwebsockets,tn0502/libwebsockets,turbulenz/libwebsockets,SoapyMan/libwebsockets,tn0502/libwebsockets,pankona/libwebsockets,peeracle/libwebsockets,IOPOINT/libwebsockets,mushroomgithub/libwebsockets,PureSwift/libwebsockets,abligh/libwebsockets,ralight/libwebsockets,cambridgehackers/libwebsockets,abligh/libwebsockets,RobertoMalatesta/libwebsockets,ralight/libwebsockets,maws/libwebsockets,jmillan/libwebsockets,SoapyMan/libwebsockets,giovanni-liboni/libwebsockets,Chilledheart/libwebsockets,maws/libwebsockets,JoakimSoderberg/libwebsockets,giovanni-liboni/libwebsockets