Fix for libgccjit 12 #227

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5 errors and 4 warnings

the feature `rustc_attrs` is internal to the compiler or standard library

the feature `staged_api` is internal to the compiler or standard library

the feature `allow_internal_unstable` is internal to the compiler or standard library

could not compile `core_arch` (lib) due to 3 previous errors

Process completed with exit code 101.

constant `EMPTY_MAX` is never used

`core` (lib test) generated 1 warning

some crates are on edition 2021 which defaults to `resolver = "2"`, but virtual workspaces default to `resolver = "1"`