Add sys crate and rename things

ffmpeg-sys-the-third/src/avutil/util.rs

@@ -0,0 +1,8 @@
+use libc::c_int;
+use {AVRational, AV_TIME_BASE};
+
+pub const AV_NOPTS_VALUE: i64 = 0x8000000000000000u64 as i64;
+pub const AV_TIME_BASE_Q: AVRational = AVRational {
+    num: 1,
+    den: AV_TIME_BASE as c_int,
+};