in gf.c jl_type_infer: why not define in_reference as atomic

[awfeequdng]

in master branch, file gf.c, function jl_type_infer: why not define in_reference as atomic

[fingolfin]

The code in there was only run if a lock was held, so no need for atomics.

But it also was replaced by different code in PR #46825.

So I think this can be closed?