Rollup merge of rust-lang#124050 - saethlin:less-sysroot-libc, r=ChrisDenton

Remove libc from MSVC targets

``@ChrisDenton`` started working on a project to remove libc from Windows MSVC targets. I'm completing that work here.

The primary change is to cfg out the dependency in `library/`. And then there's a lot of test patching. Happy to separate this more if people want.

Author: matthiaskrgr

std/Cargo.toml

@@ -33,9 +33,6 @@ addr2line = { version = "0.21.0", optional = true, default-features = false }
 [target.'cfg(not(all(windows, target_env = "msvc")))'.dependencies]
 libc = { version = "0.2.153", default-features = false, features = ['rustc-dep-of-std'], public = true }
 
-[target.'cfg(all(windows, target_env = "msvc"))'.dependencies]
-libc = { version = "0.2.153", default-features = false }
-
 [target.'cfg(all(not(target_os = "aix"), not(all(windows, target_env = "msvc", not(target_vendor = "uwp")))))'.dependencies]
 object = { version = "0.32.0", default-features = false, optional = true, features = ['read_core', 'elf', 'macho', 'pe', 'unaligned', 'archive'] }
 

std/src/lib.rs

@@ -435,6 +435,7 @@ extern crate alloc as alloc_crate;
 // so include it here even if it's unused.
 #[doc(masked)]
 #[allow(unused_extern_crates)]
+#[cfg(not(all(windows, target_env = "msvc")))]
 extern crate libc;
 
 // We always need an unwinder currently for backtraces

std/src/os/raw/tests.rs

@@ -1,3 +1,5 @@
+#![cfg(not(all(windows, target_env = "msvc")))]
+
 use crate::any::TypeId;
 
 macro_rules! ok {