sys: Fix clippy lints, run cargo fmt

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

@@ -17,7 +17,7 @@ pub unsafe fn av_cmp_q(a: AVRational, b: AVRational) -> c_int {
     } else if a.num != 0 && b.num != 0 {
         ((i64::from(a.num) >> 31) - (i64::from(b.num) >> 31)) as c_int
     } else {
-        c_int::min_value()
+        c_int::MIN
     }
 }