Don't depend on libc for cfg(windows)

Author: saethlin

crates/std_detect/Cargo.toml

@@ -21,14 +21,16 @@ is-it-maintained-open-issues = { repository = "rust-lang/stdarch" }
 maintenance = { status = "experimental" }
 
 [dependencies]
-libc = { version = "0.2", optional = true, default-features = false }
 cfg-if = "1.0.0"
 
 # When built as part of libstd
 core = { version = "1.0.0", optional = true, package = "rustc-std-workspace-core" }
 compiler_builtins = { version = "0.1.2", optional = true }
 alloc = { version = "1.0.0", optional = true, package = "rustc-std-workspace-alloc" }
 
+[target.'cfg(not(windows))'.dependencies]
+libc = { version = "0.2.0", optional = true, default-features = false }
+
 [dev-dependencies]
 cupid = "0.6.0"