According to the Cargo Reference:
https://doc.rust-lang.org/cargo/reference/manifest.html
> This is an SPDX 2.1 license expression for this package. Currently
> crates.io will validate the license provided against a whitelist of
> known license and exception identifiers from the SPDX license list
> 2.4. Parentheses are not currently supported.
>
> Multiple licenses can be separated with a `/`, although that usage
> is deprecated. Instead, use a license expression with AND and OR
> operators to get more explicit semantics.
This commit updates the `ToolBuild` step to stream Cargo's JSON messages, parse
them, and record all libraries built. If we build anything twice (aka Cargo)
it'll most likely happen due to dependencies being recompiled which is caught by
this check.
This commit
* Refactors the collect_lib_features function to work in a
non-checking mode (no bad pointer needed, and list of
lang features).
* Introduces checking whether unstable/stable tags for a
given feature have inconsistent tracking issues.
* Fixes such inconsistencies throughout the codebase.
