Ensure that the sysroot uses its own libc

ctr-std/Cargo.toml

@@ -9,12 +9,9 @@ git = "https://github.com/rust-lang-nursery/compiler-builtins"
 [dependencies.alloc_system]
 git = "https://github.com/rust3ds/alloc_system3ds"
 
-[dependencies.libc]
-version = "0.2"
-default-features = false
-
 [dependencies.ctru-sys]
 path = "../ctru-sys"
+default-features = false
 features = ["stdbuild"]
 
 [features]

ctru-sys/Cargo.toml

@@ -7,8 +7,11 @@ license = "https://en.wikipedia.org/wiki/Zlib_License"
 [dependencies.libc]
 version = "0.2"
 default-features = false
+optional = true
 
 [features]
+default = ["libc"]
+
 # This is a dummy feature that only exists to work around a Xargo issue.
 # User code should not enable it.
 stdbuild = []

ctru-sys/src/lib.rs

@@ -7,6 +7,8 @@
 
 #![no_std]
 
+#![cfg_attr(feature = "stdbuild", feature(libc))]
+
 extern crate libc;
 
 include!("bindings.rs");