master 7474b55e28: Fix setting stipple via `set-face-stipple'

[Po Lu]

branch: master
commit 7474b55e2812ec11f55817429b5e8815710e5112
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Fix setting stipple via `set-face-stipple'
    
    * lisp/faces.el (face-valid-attribute-values): Return results
    for `:stipple' in correct format.
---
 lisp/faces.el | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lisp/faces.el b/lisp/faces.el
index 395ea315ba..1ada05a7b8 100644
--- a/lisp/faces.el
+++ b/lisp/faces.el
@@ -1203,7 +1203,8 @@ an integer value."
             'integerp)
            (:stipple
             (and (memq (window-system frame) '(x ns pgtk haiku)) ; No stipple 
on w32
-                 (mapcar #'list
+                 (mapcar (lambda (item)
+                           (cons item item))
                          (apply #'nconc
                                 (mapcar (lambda (dir)
                                           (and (file-readable-p dir)