- Removes a layer of indirection in the storage of the completion
callback.
- Handles user tab completion in a task in which `complete` hasn't been
properly. Previously, if `complete` was called in one task, and `read`
called in another, attempting to get completions would crash. This
makes the completion handlers non-ambiguously task-local only.
- Fix a mismatch in return values between the Rust code and linenoise.
.with_c_str() is a replacement for the old .as_c_str(), to avoid
unnecessary boilerplate.
Replace all usages of .to_c_str().with_ref() with .with_c_str().
If the TLS key is 0-sized, then the linux linker is apparently smart enough to
put everything at the same pointer. OSX on the other hand, will reserve some
space for all of them. To get around this, the TLS key now actuall consumes
space to ensure that it gets a unique pointer
