moving SCCS later in vc-handled-backends

[Dan Nicolaescu]

When opening any version controlled file that is under one of the more
modern VCs, SCCS is tried first.
Given that it's not a popular system, this is pure overhead, so it would
be better move it at the end of vc-handled-backends.
Any objection to this change:

--- vc-hooks.el  23 Jun 2009 06:35:43 -0000     1.278
+++ vc-hooks.el  23 Jun 2009 06:39:31 -0000
@@ -60,7 +60,7 @@ interpreted as hostnames."
   :type 'regexp
   :group 'vc)
 
-(defcustom vc-handled-backends '(RCS CVS SVN SCCS Bzr Git Hg Mtn Arch)
+(defcustom vc-handled-backends '(RCS CVS SVN Bzr Git Hg Mtn SCCS Arch)
   ;; RCS, CVS, SVN and SCCS come first because they are per-dir
   ;; rather than per-tree.  RCS comes first because of the multibackend
   ;; support intended to use RCS for local commits (with a remote CVS server).