Add ocamlnet 3.7.5

On Tue, 2 Sep 2014 00:42:16 -0700, Anil Madhavapeddy wrote:
> 
> In packages/ocamlnet/ocamlnet.3.7.5/files/robust-host.patch:
> 
> > +                          (self :> < >)
> > +                          auth_cache
> > +diff --git a/src/netclient/http_client.mli b/src/netclient/http_client.mli
> > +index 9934f5f..5231083 100644
> > +--- a/src/netclient/http_client.mli
> > ++++ b/src/netclient/http_client.mli
> > +@@ -761,6 +761,9 @@ object
> > + 
> > +       If it is not possible to continue, the method may raise [Not_found].
> > +    *)
> > ++
> > ++  method default_port : int option
> > ++  (** If set, the [Host] header omits this port number *)
> > + end
> 
> is this patch upstream?

I mentioned to Gerd that I backported his fix for ocamlnet 4 but he does not seem to have applied the patch.