[4.0] 825ecef req.backend is gone now. req.backend_hint is it.

[Per Buer]

commit 825ecef42dabfc43076624dc0e5de97bf6f67d35
Author: Per Buer <perbu at varnish-software.com>
Date:   Wed Mar 5 14:19:07 2014 +0100

    req.backend is gone now. req.backend_hint is it.

diff --git a/lib/libvmod_directors/vmod.vcc b/lib/libvmod_directors/vmod.vcc
index 4905858..67ad069 100644
--- a/lib/libvmod_directors/vmod.vcc
+++ b/lib/libvmod_directors/vmod.vcc
@@ -74,7 +74,7 @@ $Method BACKEND .backend()
 Description
        Picks a backend from the director.
 Example
-       req.backend = rrdir.backend();
+       req.backend_hint = rrdir.backend();
 
 $Object fallback()
 
@@ -95,7 +95,7 @@ $Method BACKEND .backend()
 Description
        Picks a backend from the director.
 Example
-       req.backend = rrdir.backend();
+       req.backend_hint = rrdir.backend();
 
 $Object random()
 
@@ -121,7 +121,7 @@ $Method BACKEND .backend()
 Description
        Picks a backend from the director.
 Example
-       req.backend = rrdir.backend();
+       req.backend_hint = rrdir.backend();
 
 $Object hash()
 
@@ -147,5 +147,5 @@ Description
        strings provided to pick the backend.
 Example
        # pick a backend based on the cookie header from the client
-       req.backend = hdir.backend(req.http.cookie);
+       req.backend_hint = hdir.backend(req.http.cookie);