Prevent mixing deprecated check-cfg syntax with new one

[Urgau]

This PR puts an hard error when trying to mix the deprecated check-cfg syntax with new one, doing that required updating the libc crate crate to version 0.2.150 (this also means making use of the new syntax when building stage 2 and above as libc isn't granular enough).

This was previously attempted in #117025 but had to be striped out due to the libc crate not being compliant.

While preventing the mixing isn't necessary per se, it will help make sure that we are going to be ready when removing the deprecated syntax.

r? @petrochenkov

[rustbot]

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

[rust-log-analyzer]

The job x86_64-gnu-llvm-15 failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

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---
##[group]Building stage1 library artifacts (x86_64-unknown-linux-gnu)
error: failed to run `rustc` to learn about target-specific information

Caused by:
  process didn't exit successfully: `/checkout/obj/build/bootstrap/debug/rustc - --crate-name ___ --print=file-names --crate-type bin --crate-type rlib --crate-type dylib --crate-type cdylib --crate-type staticlib --crate-type proc-macro --print=sysroot --print=split-debuginfo --print=crate-name --print=cfg` (exit status: 1)
  --- stderr
  error: invalid `--check-cfg` argument: `cfg(bootstrap)` (expected `names(name1, name2, ... nameN)` or `values(name, "value1", "value2", ... "valueN")`)
Build completed unsuccessfully in 0:03:17
  local time: Sun Nov  5 15:41:20 UTC 2023
  network time: Sun, 05 Nov 2023 15:41:20 GMT
##[error]Process completed with exit code 1.

[Urgau]

Hum. This may not be possible yet, I forgot that we still use beta Cargo, even for stage 2 and above.

@rustbot author
@rustbot blocked

[Urgau]

I don't think this is is gonna work out before the next Cargo bump, at which point we will remove the old syntax, rendering this PR useless.

Closing for now.