Fix argument handling in rustic-cargo-clippy-rerun

This fixes two separate bugs.

The first caused `rustic-cargo-clippy-rerun` to not pass any effective
arguments to `rustic-cargo-clippy-run`, so the resulting run would
always have no arguments.

The second causes `rustic-cargo-clippy-rerun` to pass
`rustic-clippy-arguments` even when it's not set. This was
inconsistent with `rustic-cargo-clippy` which would fall back to
`rustic-default-clippy-arguments` when `rustic-clippy-arguments` was
empty.

rustic-clippy.el

@@ -92,7 +92,9 @@ When calling this function from `rustic-popup-mode', always use the value of
 (defun rustic-cargo-clippy-rerun ()
   "Run 'cargo clippy' with `rustic-clippy-arguments'."
   (interactive)
-  (rustic-cargo-clippy-run rustic-clippy-arguments))
+  (rustic-cargo-clippy-run :params (if (> (length rustic-clippy-arguments) 0)
+                                       rustic-clippy-arguments
+                                     rustic-default-clippy-arguments)))
 
 (defun rustic-cargo-clippy-fix (&rest args)
   "Run 'clippy fix'."