modules/{http,watchdog}: fix stability problems

As first noted in commit d1a229ae, in some cases we do call chains that
are not supported for JIT in LuaJIT.

I'm not 100% sure all of these are needed to comply, but the functions
here are really small and probably not to be that heavily used,
so I don't think it will be costly to interpret them
(and avoiding crashes is more important).

In my tests this fixed occasional crashes when using http://*/trace/*