fix heap corruption if HTTP callback calls libwebsocket_close_and_free_session
fix heap corruption if HTTP callback calls libwebsocket_close_and_free_session

Signed-off-by: Nick Dowell <75ef9faee755c70589550b513ad881e5a603182c@nickdowell.com>

lukasz-skalski/libwebsockets,sanyaade-teachings/libwebsockets,eagafonov/libwebsockets,JoakimSoderberg/libwebsockets,sartura/libwebsockets,JoakimSoderberg/libwebsockets,DaYeSquad/libwebsockets,weimingtom/libwebsockets,mushroomgithub/libwebsockets,weimingtom/libwebsockets,ayosec/libwebsockets,labatrockwell/libwebsockets,kaostao/libwebsockets,pombredanne/libwebsockets,gameclosure/libwebsockets,mctully/libwebsockets,DaYeSquad/libwebsockets,gameclosure/libwebsockets,dtebbs/libwebsockets,cambridgehackers/libwebsockets,jmillan/libwebsockets,abligh/libwebsockets,canopy-project/libwebsockets-canopy,Chilledheart/libwebsockets,eagafonov/libwebsockets,weimingtom/libwebsockets,jmillan/libwebsockets,dumganhar/libwebsockets,labatrockwell/libwebsockets,lukasz-skalski/libwebsockets,gameclosure/libwebsockets,pankona/libwebsockets,sanyaade-teachings/libwebsockets,lukasz-skalski/libwebsockets,GroundControl-Solutions/libwebsockets,mushroomgithub/libwebsockets,JoakimSoderberg/libwebsockets,mralexgray/libwebsockets-xcode,pebble/libwebsockets,cambridgehackers/libwebsockets,turbulenz/libwebsockets,Chilledheart/libwebsockets,pebble/libwebsockets,ayosec/libwebsockets,RobertoMalatesta/libwebsockets,labatrockwell/libwebsockets,sanyaade-teachings/libwebsockets,SoapyMan/libwebsockets,sartura/libwebsockets,FabianAussems/libwebsockets,abligh/libwebsockets,mctully/libwebsockets,SoapyMan/libwebsockets,sartura/libwebsockets,abligh/libwebsockets,maws/libwebsockets,bovine/libwebsockets-bovine,DaYeSquad/libwebsockets,SoapyMan/libwebsockets,dtebbs/libwebsockets,GroundControl-Solutions/libwebsockets,IOPOINT/libwebsockets,peeracle/libwebsockets,wenqiwooo/syslog-libwebsockets,kaostao/libwebsockets,kaostao/libwebsockets,ralight/libwebsockets,SoapyMan/libwebsockets,DaYeSquad/libwebsockets,sartura/libwebsockets,GroundControl-Solutions/libwebsockets,dumganhar/libwebsockets,pombredanne/libwebsockets,cambridgehackers/libwebsockets,PureSwift/libwebsockets,ayosec/libwebsockets,PureSwift/libwebsockets,ralight/libwebsockets,peeracle/libwebsockets,antmicro/libwebsockets,gameclosure/libwebsockets,giovanni-liboni/libwebsockets,peeracle/libwebsockets,pebble/libwebsockets,IOPOINT/libwebsockets,canopy-project/libwebsockets-canopy,sartura/libwebsockets,maws/libwebsockets,GroundControl-Solutions/libwebsockets,pombredanne/libwebsockets,mralexgray/libwebsockets-xcode,jmillan/libwebsockets,wenqiwooo/syslog-libwebsockets,DaYeSquad/libwebsockets,pebble/libwebsockets,sanyaade-teachings/libwebsockets,RobertoMalatesta/libwebsockets,peeracle/libwebsockets,bovine/libwebsockets-bovine,turbulenz/libwebsockets,abligh/libwebsockets,ayosec/libwebsockets,tn0502/libwebsockets,canopy-project/libwebsockets-canopy,SoapyMan/libwebsockets,IOPOINT/libwebsockets,eagafonov/libwebsockets,wenqiwooo/syslog-libwebsockets,antmicro/libwebsockets,turbulenz/libwebsockets,dtebbs/libwebsockets,FabianAussems/libwebsockets,mralexgray/libwebsockets-xcode,Chilledheart/libwebsockets,RobertoMalatesta/libwebsockets,dumganhar/libwebsockets,FabianAussems/libwebsockets,pankona/libwebsockets,maws/libwebsockets,ralight/libwebsockets,kaostao/libwebsockets,pombredanne/libwebsockets,giovanni-liboni/libwebsockets,ayosec/libwebsockets,dumganhar/libwebsockets,sartura/libwebsockets,peeracle/libwebsockets,mushroomgithub/libwebsockets,PureSwift/libwebsockets,maws/libwebsockets,ralight/libwebsockets,RobertoMalatesta/libwebsockets,bovine/libwebsockets-bovine,giovanni-liboni/libwebsockets,bovine/libwebsockets-bovine,weimingtom/libwebsockets,wenqiwooo/syslog-libwebsockets,ralight/libwebsockets,labatrockwell/libwebsockets,lukasz-skalski/libwebsockets,JoakimSoderberg/libwebsockets,mctully/libwebsockets,sartura/libwebsockets,tn0502/libwebsockets,eagafonov/libwebsockets,tn0502/libwebsockets,jmillan/libwebsockets,giovanni-liboni/libwebsockets,mushroomgithub/libwebsockets,PureSwift/libwebsockets,antmicro/libwebsockets,pankona/libwebsockets,Chilledheart/libwebsockets,pankona/libwebsockets,tn0502/libwebsockets,dumganhar/libwebsockets,FabianAussems/libwebsockets,cambridgehackers/libwebsockets,GroundControl-Solutions/libwebsockets,antmicro/libwebsockets,dtebbs/libwebsockets,PureSwift/libwebsockets,mralexgray/libwebsockets-xcode