Fix stale references to legacy module names

- ocsigen_stream.mli: comment mentioned [Ocsigen_config], update to
  [Ocsigen.Config].
- Delete ocsigen_config_static.ml.in: legacy autotools-era template
  no longer used by the dune build (which generates
  Ocsigen_base/config_static.ml via gen.exe).

Author: balat

src/baselib/Ocsigen_base/ocsigen_stream.mli

@@ -129,6 +129,6 @@ end
 
 (**/**)
 
-(* Small hack that will allow us to move [Ocsigen_config] out of
+(* Small hack that will allow us to move [Ocsigen.Config] out of
    baselib. Not super-pretty. *)
 val set_net_buffer_size : int -> unit