rustc prints the warning:
`-C save-temps` might not produce all requested temporary
products when incremental compilation is enabled.
However, incremental compilation isn't even enabled.
A look at the Rust source code confirms that this warning is indeed
printed unconditionally when the `-C save-temps` flag is specified:
5f2b325f64/src/librustc/session/config.rs (L1015-L1018)
Move rust.gni and deno.gni into build_extra/
Removes rust_library which was only an action. This instead defines
rust_component, which is an action plus a gn "component" target
to expose the resulting object file. This simplifies link code in
rust.gni.
Support rust modules that can be linked into C++.
