Export AbsoluteLabel functionality (#1568)
Export AbsoluteLabel functionality (#1568)

So that [crubit](https://github.com/google/crubit)'s (upcoming) equivalent `cc_import!` macro can reuse the code.
bazelbuild/rules_rust,bazelbuild/rules_rust,bazelbuild/rules_rust,bazelbuild/rules_rust,bazelbuild/rules_rust