Depend on libc from crates.io

Cargo.lock

@@ -3694,6 +3694,7 @@ dependencies = [
  "indexmap",
  "jobserver",
  "lazy_static 1.4.0",
+ "libc",
  "log",
  "measureme",
  "parking_lot 0.10.0",
@@ -3713,6 +3714,7 @@ version = "0.0.0"
 dependencies = [
  "env_logger 0.7.1",
  "lazy_static 1.4.0",
+ "libc",
  "log",
  "rustc_ast",
  "rustc_ast_pretty",
@@ -3867,6 +3869,7 @@ dependencies = [
 name = "rustc_interface"
 version = "0.0.0"
 dependencies = [
+ "libc",
  "log",
  "once_cell",
  "rustc-rayon",
@@ -3960,6 +3963,7 @@ name = "rustc_metadata"
 version = "0.0.0"
 dependencies = [
  "flate2",
+ "libc",
  "log",
  "memmap",
  "rustc_ast",

src/librustc_data_structures/Cargo.toml

@@ -27,6 +27,7 @@ smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 rustc_index = { path = "../librustc_index", package = "rustc_index" }
 bitflags = "1.2.1"
 measureme = "0.7.1"
+libc = "0.2"
 
 [dependencies.parking_lot]
 version = "0.10"

src/librustc_data_structures/lib.rs

@@ -26,8 +26,6 @@
 
 #[macro_use]
 extern crate log;
-#[cfg(unix)]
-extern crate libc;
 #[macro_use]
 extern crate cfg_if;
 

src/librustc_driver/Cargo.toml

@@ -11,6 +11,7 @@ crate-type = ["dylib"]
 
 [dependencies]
 lazy_static = "1.0"
+libc = "0.2"
 log = "0.4"
 env_logger = { version = "0.7", default-features = false }
 rustc_middle = { path = "../librustc_middle" }

src/librustc_driver/lib.rs

@@ -9,8 +9,6 @@
 #![recursion_limit = "256"]
 
 pub extern crate getopts;
-#[cfg(unix)]
-extern crate libc;
 #[macro_use]
 extern crate log;
 #[macro_use]

src/librustc_interface/Cargo.toml

@@ -10,6 +10,7 @@ path = "lib.rs"
 doctest = false
 
 [dependencies]
+libc = "0.2"
 log = "0.4"
 rayon = { version = "0.3.0", package = "rustc-rayon" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }

src/librustc_interface/lib.rs

@@ -6,9 +6,6 @@
 #![feature(generators)]
 #![recursion_limit = "256"]
 
-#[cfg(unix)]
-extern crate libc;
-
 mod callbacks;
 pub mod interface;
 mod passes;

src/librustc_metadata/Cargo.toml

@@ -11,6 +11,7 @@ doctest = false
 
 [dependencies]
 flate2 = "1.0"
+libc = "0.2"
 log = "0.4"
 memmap = "0.7"
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }

src/librustc_metadata/lib.rs

@@ -10,7 +10,6 @@
 #![feature(stmt_expr_attributes)]
 #![recursion_limit = "256"]
 
-extern crate libc;
 extern crate proc_macro;
 
 #[macro_use]