Fix warnings and reduce scope of libc (#166)

Cargo.toml

@@ -9,7 +9,6 @@ license = "Apache-2.0"
 keywords = ["audio", "sound"]
 
 [dependencies]
-libc = "0.2"
 lazy_static = "0.2"
 
 [target.'cfg(target_os = "windows")'.dependencies]
@@ -19,6 +18,7 @@ kernel32-sys = "0.2"
 
 [target.'cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd", target_os = "openbsd"))'.dependencies]
 alsa-sys = { version = "0.1", path = "alsa-sys" }
+libc = "0.2"
 
 [target.'cfg(any(target_os = "macos", target_os = "ios"))'.dependencies]
 coreaudio-rs = "0.7.0"

examples/beep.rs

@@ -1,9 +1,5 @@
 extern crate cpal;
 
-use std::sync::Arc;
-use std::thread;
-use std::time::Duration;
-
 fn main() {
     let endpoint = cpal::default_endpoint().expect("Failed to get default endpoint");
     let format = endpoint

src/alsa/enumerate.rs

@@ -1,14 +1,12 @@
-
 use super::Endpoint;
 use super::alsa;
+use super::libc;
 use super::check_errors;
 
 use std::ffi::CStr;
 use std::ffi::CString;
 use std::mem;
 
-use libc;
-
 /// ALSA implementation for `EndpointsIterator`.
 pub struct EndpointsIterator {
     // we keep the original list so that we can pass it to the free function

src/coreaudio/mod.rs

@@ -1,5 +1,4 @@
 extern crate coreaudio;
-extern crate libc;
 
 use ChannelPosition;
 use CreationError;

src/lib.rs

@@ -39,7 +39,6 @@ from time to time.
 
 #[macro_use]
 extern crate lazy_static;
-extern crate libc;
 
 pub use samples_formats::{Sample, SampleFormat};
 

src/wasapi/voice.rs

@@ -6,14 +6,12 @@ use super::kernel32;
 use super::ole32;
 use super::winapi;
 
-use std::iter;
 use std::marker::PhantomData;
 use std::mem;
 use std::ptr;
 use std::slice;
 use std::sync::atomic::AtomicUsize;
 use std::sync::atomic::Ordering;
-use std::sync::Arc;
 use std::sync::Mutex;
 
 use ChannelPosition;