cargo: add features for every library

sys/Cargo.toml

@@ -1,7 +1,18 @@
 [package]
-name = "ffmpeg-sys"
+name    = "ffmpeg-sys"
 version = "2.6.2-1"
+
 authors = ["meh. <meh@schizofreni.co>"]
 license = "WTFPL"
+
 description = "FFI bindings to FFmpeg"
-repository = "https://github.com/meh/rust-ffmpeg-sys"
+repository  = "https://github.com/meh/rust-ffmpeg-sys"
+
+[features]
+default  = ["avcodec", "avdevice", "avformat", "postproc", "swscale"]
+
+avcodec  = []
+avdevice = ["avformat"]
+avformat = ["avcodec"]
+postproc = []
+swscale  = []

sys/src/lib.rs

@@ -7,17 +7,27 @@ extern crate libc;
 mod avutil;
 pub use avutil::*;
 
+#[cfg(feature = "avcodec")]
 mod avcodec;
+#[cfg(feature = "avcodec")]
 pub use avcodec::*;
 
+#[cfg(feature = "avdevice")]
 mod avdevice;
+#[cfg(feature = "avdevice")]
 pub use avdevice::*;
 
+#[cfg(feature = "avformat")]
 mod avformat;
+#[cfg(feature = "avformat")]
 pub use avformat::*;
 
+#[cfg(feature = "swscale")]
 mod swscale;
+#[cfg(feature = "swscale")]
 pub use swscale::*;
 
+#[cfg(feature = "postproc")]
 mod postproc;
+#[cfg(feature = "postproc")]
 pub use postproc::*;