Signed-off-by: onur-ozkan <work@onurozkan.dev>

This change introduces the --skip-stage0-validation flag,
which permits the use of any desired version of the stage0
compiler without verifying its version.

Signed-off-by: onur-ozkan <work@onurozkan.dev>

…sumption

Simplify #[cfg] blocks

fmt

don't try to use the more appropriate direntry on musl

This should hopefully reduce memory usage and improve performance since
these vectors are often empty (and `GenericParamDefKind` is constructed
*a lot*).

Don't use LFS64 symbols on musl

Supersedes rust-lang#106246

~~Note to packagers: If your distro's musl package has already been updated, then you won't be able to build a newer version of rust until a new rust release is made with these changes merged (which can be used to bootstrap). I'm using a super hacky method to bypass this by creating a stub library with LFS64 symbols and building a patched rust, so the symbols satisfy the build requirements while the final compiler build has no references to LFS64 symbols, example: https://codeberg.org/kiss-community/repo/pulls/160/files~~ Doesn't seem to be necessary with new rustup nightly builds, likely due to updates to vendored crates

cc ```@alyssais```

… r=Mark-Simulacrum

add bootstrap flag `--skip-stage0-validation`

This change introduces the `--skip-stage0-validation` flag, which permits the use of any desired version of the stage0 compiler without verifying its version.

Additionally, stage0 compiler validation check is reverted(rust-lang#115103) to its default enabled state.

Helps to rust-lang#115065

r? Mark-Simulacrum

…_target_feature_sgx, r=Mark-Simulacrum

Fix closure-inherit-target-feature test for SGX platform

PR rust-lang#116078 adds the `closure-inherit-target-feature.rs` test that checks the generated assembly code for closures. These checks explicitly check the presence of `ret` instructions. This is incompatible with the SGX target as it explicitly rewrites all `ret` instructions to mitigate LVI vulnerabilities of certain processors. This PR simply ignores these tests for the SGX platform.

cc: ```@jethrogb```

…k-Simulacrum

memcpy assumptions: link to source showing that GCC makes the same assumption

I finally stumbled upon a source showing that GCC also generates overlapping `memcpy`. So if we're linking major C compilers making such assumptions here, let's have both clang and GCC.

…=GuillaumeGomez

rustdoc: Use `ThinVec` in `GenericParamDefKind`

This should hopefully reduce memory usage and improve performance since
these vectors are often empty (and `GenericParamDefKind` is constructed *a lot*).