Fixed dead code warnings

Closes https://github.com/AngryLawyer/rust-sdl2/issues/127

src/sdl2/audio.rs

@@ -58,6 +58,7 @@ pub mod ll {
         ::std::option::Option<extern "C" fn
                                   (arg1: *SDL_AudioCVT,
                                    arg2: SDL_AudioFormat)>;
+    #[allow(dead_code)]
     pub struct SDL_AudioCVT {
         pub needed: c_int,
         pub src_format: SDL_AudioFormat,

src/sdl2/controller.rs

@@ -16,15 +16,18 @@ pub mod ll {
     pub static SDL_CONTROLLER_BINDTYPE_AXIS: SDL_GameControllerBindType = 2;
     pub static SDL_CONTROLLER_BINDTYPE_HAT: SDL_GameControllerBindType = 3;
 
+    #[allow(dead_code)]
     pub struct SDL_GameControllerButtonBind {
         bindType: SDL_GameControllerBindType,
         value: SDL_GameControllerButtonBindData,
     }
 
+    #[allow(dead_code)]
     pub struct SDL_GameControllerButtonBindData {
         data: [c_uchar, ..8u],
     }
 
+    #[allow(dead_code)]
     pub struct SDL_GameControllerButtonBindDataHat {
         hat: c_int,
         hat_mask: c_int,

src/sdl2/joystick.rs

@@ -6,6 +6,7 @@ pub mod ll {
 
     pub type SDL_Joystick = c_void;
 
+    #[allow(dead_code)]
     pub struct SDL_JoystickGUID {
         data: [uint8_t, ..16u],
     }

src/sdl2/rwops.rs

@@ -9,6 +9,7 @@ pub mod ll {
     use libc::{c_uchar, uint32_t, c_char, FILE, c_void};
     use libc::{c_int, int64_t, size_t};
 
+    #[allow(dead_code)]
     struct SDL_RWops_Anon {
         data: [c_uchar, ..24],
     }
@@ -19,6 +20,7 @@ pub mod ll {
     pub static RW_SEEK_CUR: c_int = 1;
     pub static RW_SEEK_END: c_int = 2;
 
+    #[allow(dead_code)]
     pub struct SDL_RWops {
         pub size:  extern "C" fn(context: *SDL_RWops) -> int64_t,
         pub seek:  extern "C" fn(context: *SDL_RWops, offset: int64_t, whence: c_int) -> int64_t,