Fix uses of include module type of

Ensure that type equations are also propagated.

src/core/opamCompat.mli

@@ -13,7 +13,7 @@ module String
 = String
 #else
 : sig
-  include module type of String
+  include module type of struct include String end
 
   val lowercase_ascii : string -> string
   val uppercase_ascii : string -> string
@@ -26,7 +26,7 @@ module Char
 = Char
 #else
 : sig
-  include module type of Char
+  include module type of struct include Char end
 
   val lowercase_ascii: char -> char
 end
@@ -37,7 +37,7 @@ module Printexc
 = Printexc
 #else
 : sig
-  include module type of Printexc
+  include module type of struct include Printexc end
 
   val raise_with_backtrace: exn -> raw_backtrace -> 'a
 end
@@ -48,7 +48,7 @@ module Unix
 = Unix
 #else
 : sig
-  include module type of Unix
+  include module type of struct include Unix end
 
   val map_file : Unix.file_descr -> ?pos:int64 -> ('a, 'b) Bigarray.kind ->
                  'c Bigarray.layout -> bool -> int array ->

src/format/opamTypesBase.mli

@@ -15,7 +15,7 @@
     basic OPAM types present in OpamTypes.ml *)
 open OpamTypes
 
-include module type of OpamCompat
+include module type of struct include OpamCompat end
 
 val string_of_std_path: std_path -> string
 val std_path_of_string: string -> std_path

src/solver/opamCudfSolver.mli

@@ -12,7 +12,7 @@
     relying on external solvers (aspcud, etc.). Used for calling-back below
     Dose. *)
 
-include module type of OpamCudfSolverSig
+include module type of struct include OpamCudfSolverSig end
 
 module Aspcud : S
 module Aspcud_old : S