Extern/scope issue

[DLearner]

> extern(L) extern otherQualifiersIfAny variableType 
> variableName; //appears to be a variable declared outside of 
> the module, so at link time a .obj file will have to declare a 
> variable with this symbol name or else the linker will error 
> out.
> ```
> It seems that case 4 is what you desired but i do not know if 
> with this module hierarchy it can/will work with dub.(it 
> should.)
> With the code as is you should be able to access both variables 
> from main with `testmod.xvar` and simply `xvar`.(when name 
> conflicts like this occur the most local is used by default, 
> otherwise use the full name which should be `testmain.xvar` in 
> this case.)

I tried case 4, failed with link errors.

I am not trying to establish two variables, just exactly the same 
one everywhere.
That's why the desired test output is 1,1,2,2