[Dlang-internal] Attempt to export ModuleInfo on Windows

[Rikki Cattermole]

After doing some more work on my projects I ended up getting a 
very interesting error message with ldc:

```
sidero_image-test-unittest.obj : error LNK2019: unresolved 
external symbol __imp__D6sidero4base4hash5utils12__ModuleInfoZ 
referenced in function ldc.dllimport_relocation
sidero_image-test-unittest.obj : error LNK2019: unresolved 
external symbol __imp__D6sidero4base4hash3fnv12__ModuleInfoZ 
referenced in function ldc.dllimport_relocatio
```

What is interesting about this little error is that it is 
referencing the DllImport symbols from a ldc function. Generated 
from [0]. It's doing additional patching on top of the OS linker 
which is effectively dereference and set at start of runtime. 
This kinda rules out that it is simply a limitation of dmd and 
instead is a conceptual problem at the system linker & codegen 
level.

So what does this mean for dmd? Well, either we copy the solution 
from ldc or we do the patching as needed. I think patching as 
needed may be the best bet, but that means changing druntime in 
two places with an additional memory allocation when calling 
importedModules.

[0] 
https://github.com/ldc-developers/ldc/blob/03e35c5ce57e665e89f5ee2efeaffe958ba815d4/gen/passes/DLLImportRelocation.cpp#L183