Merge branch 'ptr-offset-by-literal-lint' into 'master'

add ptr_offset_by_literal clippy lint and set to deny

See merge request redox-os/relibc!1527

src/header/unistd/mod.rs

@@ -604,7 +604,7 @@ pub unsafe extern "C" fn gethostname(mut name: *mut c_char, mut len: size_t) ->
             break;
         }
 
-        name = unsafe { name.offset(1) };
+        name = unsafe { name.add(1) };
     }
     0
 }