self: Display a new line at the end of module compilation.

* guix/self.scm (compiled-modules)[build]: Add a 'newline' call at the
end.

guix/self.scm

@@ -543,7 +543,8 @@ (define (process-directory directory output)
 
           (mkdir #$output)
           (chdir #+module-tree)
-          (process-directory "." #$output))))
+          (process-directory "." #$output)
+          (newline))))
 
   (computed-file name build
                  #:guile guile-for-build