Make T{typeof(f)}() loadable again

[kshramt]

This patch fixes a regression introduced by 94af823.
Now the return value of Optim.optimize is loadable again.

[kshramt]

CI failures seem to be unrelated.

[vtjnash]

This should be fixed with a custom Symbol printer at locations such as
https://github.com/kshramt/JLD.jl/blob/071d0e16d3d44a0f29e5f0d9b1126246e4d1694e/src/JLD.jl?utf8=✓#L1127
which prints out getfield(mod.path, Symbol("name")) instead of mod.path.name when name can't be represented as a Symbol. (for bonus points, it could also write mod.path.#sin as typeof(mod.path.sin), but that's not strictly necessary).