Rollup merge of #142297 - jieyouxu:needs-target-std, r=Kobzol

Implement `//@ needs-target-std` compiletest directive

Closes rust-lang/rust#141863.
Needed to unblock rust-lang/rust#139244 and rust-lang/rust#141856.

### Summary

This PR implements a `//@ needs-target-std` compiletest directive that gates test execution based on whether the target supports std or not. For some cases, this should be preferred over e.g. some combination of `//@ ignore-none`, `//@ ignore-nvptx` and more[^none-limit].

### Implementation limitation

Unfortunately, since there is currently [no reliable way to determine from metadata whether a given target supports std or not](rust-lang/rust#142296), we have to resort to a hack. Bootstrap currently determines whether or not a target supports std by a naive target tuple substring comparison: a target supports std if its target tuple does *not* contain one of `["-none", "nvptx", "switch"]` substrings. This PR simply pulls that hack out into `build_helpers` to avoid reimplementing the same hack in compiletest, and uses that logic to inform `//@ needs-target-std`.

### Auxiliary changes

This PR additionally changes a few run-make tests to use `//@ needs-target-std` over an inconsistent combination of target-based `ignore`s. This should help with rust-lang/rust#139244.

---

r? bootstrap

[^none-limit]: Notably, `target_os = "none"` is **not** a sufficient condition for "target does not support std"

Author: matthiaskrgr

src/tests/directives.md

@@ -202,6 +202,7 @@ settings:
   `//@ needs-crate-type: cdylib, proc-macro` will cause the test to be ignored
   on `wasm32-unknown-unknown` target because the target does not support the
   `proc-macro` crate type.
+- `needs-target-std` — ignores if target platform does not have std support.
 
 The following directives will check LLVM support: