The static version of the standard library was leaking symbols in the
`llvm::` namespace which would result in ODR violations were the
artifact linking against `LLVMSupport` (via another dependency). In
particular, `llvm::SmallVector` and `llvm::StringSwitch` symbols were
being leaked. This adds a test case specifically for the static variant
of the library. The dynamic variant of the library is already tested in
a separate test.
