Segfault on OpaqueClosure MethodInstance registration

[wsmoses]

Tested on 1.10 locally.

Compiling and running an opaque closure eventually calls registerJITObject

julia/src/debuginfo.cpp

Line 224 in 4976d05

void JITDebugInfoRegistry::registerJITObject(const object::ObjectFile &Object,

This maps the JIT address to the methodinstance globally in the JIT:

julia/src/debuginfo.cpp

Line 377 in 4976d05

linfomap[Addr] = std::make_pair(Size, codeinst->def);

Later on, this will be looked up, e.g., but lookupLInfo for stacktraces.

However, it appears that the OpaqueClosure's MI is not globally rooted. Which means that it gets garbage collected. But garbage collection does not remove things from the jit registration. And thus when the stack trace mechanism tries to find it.....it segfaults

cc @vchuravy @Keno @vtjnash @gbaraldi