gnu: make-bootstrap: guile-static-stripped has no "debug" output.

* gnu/packages/make-bootstrap.scm (%guile-static-stripped): Add
  `outputs' field.

gnu/packages/make-bootstrap.scm

@@ -519,7 +519,8 @@ (define %guile-static-stripped
                       (string-append out "/bin/guile"))
            (remove-store-references (string-append out "/bin/guile"))
            #t))))
-    (inputs `(("guile" ,%guile-static)))))
+    (inputs `(("guile" ,%guile-static)))
+    (outputs '("out"))))
 
 (define (tarball-package pkg)
   "Return a package containing a tarball of PKG."