Using a development branch of druntime+phobos with ldc

[Per Nordlöw]

I'm experimenting with a new GC at

https://github.com/nordlow/druntime/blob/fastalloc-gc/src/gc/impl/fastalloc/gc.d

in my druntime branch fastalloc-gc.

I've found a way to benchmark it using dmd as outlined at

https://forum.dlang.org/post/zjxycchqrnxplkrlmnsj@forum.dlang.org

but what about rebuilding druntime+phobos with ldc and linking 
with that specific libphobos.so when compiling my benchmarking 
app with ldc? Is it possible? If so, what's the preferred way?