Manually fix remaining clippy lints

Author: MarijnS95

tests/message_from_boxed_slice.rs

@@ -26,7 +26,7 @@ static A: Allocator = Allocator;
 #[test]
 fn message_from_boxed_slice() {
     let mut b: Box<[u8]> = Box::new([0u8; 42]);
-    CHECK_PTR.store(b.as_mut_ptr() as *mut u8, Ordering::SeqCst);
+    CHECK_PTR.store(b.as_mut_ptr(), Ordering::SeqCst);
     let _ = zmq::Message::from(b);
     assert_eq!(CHECK_PTR.load(Ordering::SeqCst), ptr::null_mut());
 }

tests/monitor.rs

@@ -2,7 +2,6 @@
 mod common;
 
 use std::str;
-use std::u16;
 
 fn version_ge_4_3() -> bool {
     let (major, minor, _) = zmq::version();

tests/z85.rs

@@ -33,12 +33,12 @@ fn test_decode_errors() {
     }
 }
 
+/*
 // Valid input for z85 encoding (i.e. a slice of bytes with its length
 // being a multiple of 4)
 #[derive(Clone, Debug)]
 struct Input(Vec<u8>);
 
-/*
 // Disabled because quickcheck doesn't expose gen_range and gen anymore
 
 impl Arbitrary for Input {