This behavior is non-hermetic, but matches the behavior of the C++
support. On Linux, using lld works, but on OSX, this fails because lld
does not support Apple's new .tbd files.
Bug: 155302034
Test: On both Linux and Mac hosts:
cd external/rust; mma
Change-Id: I0ad489113d720bdb9c3b7a67cce9d1e72266f428