kill boilerplate around posix_acl_chmod_masq()

new helper: posix_acl_chmod(&acl, gfp, mode).  Replaces acl with modified
clone or with NULL if that has failed; returns 0 or -ve on error.  All
callers of posix_acl_chmod_masq() switched to that - they'd been doing
exactly the same thing.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/posix_acl.h b/include/linux/posix_acl.h
index 54211c1..7a74d37 100644
--- a/include/linux/posix_acl.h
+++ b/include/linux/posix_acl.h
@@ -80,6 +80,7 @@
 extern int posix_acl_equiv_mode(const struct posix_acl *, mode_t *);
 extern int posix_acl_create_masq(struct posix_acl *, mode_t *);
 extern int posix_acl_chmod_masq(struct posix_acl *, mode_t);
+extern int posix_acl_chmod(struct posix_acl **, gfp_t, mode_t);
 
 extern struct posix_acl *get_posix_acl(struct inode *, int);
 extern int set_posix_acl(struct inode *, int, struct posix_acl *);