Rollup merge of #145619 - joshtriplett:use-the-right-core, r=tgross35

`std_detect`: Use `rustc-std-workspace-*` to pull in `compiler-builtins`

https://github.com/rust-lang/rust/pull/145489 changed `std_detect` to no
longer depend on `cfg-if`, which meant it no longer indirectly pulled in
`rustc-std-workspace-core` via `cfg-if`. That caused it to no longer
depend on `compiler-builtins`.

Change `std_detect` to use `rustc-std-workspace-core` and
`rustc-std-workspace-alloc`, to integrate with the rustc workspace. This
also pulls in `compiler-builtins` via `rustc-std-workspace-core`.

Closes: https://github.com/rust-lang/rust/issues/145594