acl: fix specification comments

[Bruno Haible]

I found out how file_has_acl is meant to be called by looking at the coreutils
source code.


2011-10-03  Bruno Haible  <address@hidden>

        acl: Fix specification.
        * lib/file-has-acl.c (file_has_acl): Fix specification.

--- lib/file-has-acl.c.orig     Mon Oct  3 15:47:44 2011
+++ lib/file-has-acl.c  Mon Oct  3 15:47:12 2011
@@ -439,7 +439,8 @@
 
 /* Return 1 if NAME has a nontrivial access control list, 0 if NAME
    only has no or a base access control list, and -1 (setting errno)
-   on error.  SB must be set to the stat buffer of FILE.  */
+   on error.  SB must be set to the stat buffer of NAME, obtained
+   through stat() or lstat().  */
 
 int
 file_has_acl (char const *name, struct stat const *sb)