Append the Varnish default internal vcl_recv

It turns out that the mobile caches have been using (and relying)
on the default vcl_recv function that's appended by Varnish.
XFF handling is done there, and caching is killed for any and all
requests containing a Cookie header...

Appending it explicitly for visibility, and to allow removing it
one bit at a time.

Change-Id: I24287cb3bb4f1d88e6c4db6e99713984b35fe0a9
Merge "Append the Varnish default internal vcl_recv" into production