*: use latest ffmpeg-sys using bindgen

* Update bindings to newest ffmpeg version for new ffmpeg-sys, which is mostly generated by bindgen
* Bring back removed feature flags
* Fix whitespace formating
* Remove prepended enum names to enum variants
* Remove unneeded allows

src/software/resampling/context.rs

@@ -84,7 +84,7 @@ impl Context {
 	/// Get the remaining delay.
 	pub fn delay(&self) -> Option<Delay> {
 		unsafe {
-			match swr_get_delay(self.as_ptr(), 1) {
+			match swr_get_delay(self.as_ptr() as *mut _, 1) {
 				0 => None,
 				_ => Some(Delay::from(self))
 			}