Use a GAT for `Searcher` associated type because this trait is always
implemented for every lifetime anyway.

…o we should write "::core"

At some point it seems `SystemTime::new` changed from returning `SystemTime` to `io::Result<SystemTime>`. This seems to have been addressed on other platforms, but was never changed for AIX.

This was caught by running 
```
python3 x.py build --host x86_64-unknown-linux-gnu --target powerpc64-ibm-aix
```

When using download-rustc, any stage other than 0 or 1 (e.g., cargo +stage2 build/doc) will
fail to find std while compiling on simple rust sources. Ensuring the rustc step fixes
this issue.

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

Co-authored-by: Jubilee <46493976+workingjubilee@users.noreply.github.com>

Update tracking issue for `const_binary_heap_new_in`

This PR updates the tracking issue of `const_binary_heap_new_in` feature:
- Old issue: rust-lang#112353
- New issue: rust-lang#125961

Add elem_offset and related methods

Implementation of rust-lang#126769

Remove generic lifetime parameter of trait `Pattern`

Use a GAT for `Searcher` associated type because this trait is always implemented for every lifetime anyway.

cc rust-lang#27721

…ilee

Docs for core::primitive: mention that "core" can be shadowed, too, so we should write "::core"

``@rustbot`` label +A-docs

…ilee

Remove wrapper functions from c.rs

I'd like for the windows `c.rs` just to contain the basic platform definitions and not anything higher level unless absolutely necessary. So this removes some wrapper functions that weren't really necessary in any case. The functions are only used in a few places which themselves are relatively thin wrappers. The "interesting" bit is that we had an `AlertableIoFn` that abstracted over `ReadFileEx` and `WriteFileEx`. I've replaced this with a closure.

Also I removed an `#[allow(unsafe_op_in_unsafe_fn)]` while I was moving things around.

…bzol,jieyouxu

Allow to pass a full path for `run-make` tests

It's common (at least for me) to pass a full path to a `run-make` test (including the `rmake.rs` file) and to see that it isn't found, which is a bit frustrating.

With these changes, we can now optionally pass the `rmake.rs` (or even `Makefile`) at the end of the path.

cc ```@jieyouxu```
r? ```@Kobzol```

Fix return type of FileAttr methods on AIX target

At some point it seems `SystemTime::new` changed from returning `SystemTime` to `io::Result<SystemTime>`. This seems to have been addressed on other platforms, but was never changed for AIX.

This was caught by running
```
python3 x.py build --host x86_64-unknown-linux-gnu --target powerpc64-ibm-aix
```

…led-rustc, r=Kobzol

ensure std step before preparing sysroot

When using download-rustc, any stage other than 0 or 1 (e.g., cargo +stage2 build/doc) will fail to find std while compiling on simple rust sources. Ensuring the std step fixes this issue.

r? Kobzol