Rollup merge of #149624 - Flakebi:fix-lto, r=bjorn3
Fix requires_lto targets needing lto set in cargo
Targets that set `requires_lto = true` were not actually using lto when compiling with cargo by default. They needed an extra `lto = true` in `Cargo.toml` to work.
Fix this by letting lto take precedence over the `embed_bitcode` flag when lto is required by a target.
If both these flags would be supplied by the user, an error is generated. However, this did not happen when lto was requested by the target instead of the user.
Fixesrust-lang/rust#148514
Tracking issue: rust-lang/rust#135024
4b535ca2e2