fix C struct definition of LineInfoNode

[vtjnash]

Fix regression introduced by #44548. Fix #45310.

Found via rr trace in https://buildkite.com/julialang/julia-master/builds/14475#01825f4d-8c0c-4f70-938c-cd1c8ee4d202, resulting in a compiler error test calling jlbacktrace, and dereferencing invalid memory, if the object happened not to be zero initialized. Otherwise, if the undefined memory was zero initialized, it would probably instead just be missing inlined frames.

[gbaraldi]

LGTM, I don't know of a way we could automatically do some checks for errors like these, but that might be something to keep in mind

[KristofferC]

Sorry about that. :(

[vtjnash]

we can try to add some more assert(sizeof foo == jl_datatype_size foo && "layout consistency check fail"), but unsure if that would have really worked to catch this

[KristofferC]

I don't think this commit is on 1.8.