Fix crash loading Swift symbol (I think associated with concurrency)
Nathan Sobo
created
I add /usr/lib/swift as an rpath, which seems to fix the issue even though
there doesn't seem to be a relevant library at that location on my machine.
Based on my research, wondering if `-Wl,-weak-lswiftCompatibilityConcurrency`
is also required for this to work on older OSes, but holding back for now.