This is no longer necessary now that rustdoc doesn't run
everybody_loops.

This happened because `alloc_query_strings` was never called.

- Show `create_renderer` and `renderer_after_crate` by default
- Don't rewrite `extra_verbose_generic_activity`

This avoids each tool having to separately find and call
`self_profile_alloc_strings`.

- Don't compute the global context if it hasn't yet been computed

  This avoids giving extraneous errors about unresolved names if an error
  occurs during parsing.