Fix return value of 'set-file-extended-attributes'

* lisp/files.el (set-file-extended-attributes): Return non-nil
when setting either ACLs or SELinux context succeeds.  Document
the return value.  (Bug#21699)

* doc/lispref/files.texi (Changing Files): Document the return
value of set-file-extended-attributes.

1 files changed, 2 insertions, 0 deletions

diff --git a/doc/lispref/files.texi b/doc/lispref/files.texi
index 4d2761ed419..ca8abe54ace 100644
--- a/doc/lispref/files.texi
+++ b/doc/lispref/files.texi
@@ -1758,6 +1758,8 @@ time and must be in the format returned by @code{current-time}
 This function sets the Emacs-recognized extended file attributes for
 @code{filename}.  The second argument @var{attribute-alist} should be
 an alist of the same form returned by @code{file-extended-attributes}.
+The return value is @code{t} if the attributes are successfully set,
+otherwise it is @code{nil}.
 @xref{Extended Attributes}.
 @end defun