We have a de-facto policy in clang-tidy to not qualify names unless
absolutely necessary. We're *mostly* consistent about that (especially
in new code), but a number of deviations have accumulated over the
years. We even have cases where the same name is sometimes qualified and
sometimes not *in the same file*. This makes it jarring to read the
code, and, I imagine, more confusing for newcomers to contribute to the
project (do I qualify X or not?). This PR tries to improve the situation
and regularize the codebase.
6f23ba2555