llvm-go will call llvm-config --libs to get the
library names for all of the components required
to link Go code using the LLVM Go bindings. This
fails if the component libraries are not all built,
because llvm-go does not have the dependencies.
We move the dependencies off targets built with
llvm-go, and onto llvm-go itself, since llvm-go
is practically useless without them. This enables
running the Go bindings tests without building the
component libraries explicitly.