missing fixes for 4.06

how did opam this compile before?

src/cil.ml

@@ -5080,7 +5080,7 @@ let loadBinaryFile (filename : string) : file =
 (* Take the name of a file and make a valid symbol name out of it. There are 
  * a few characters that are not valid in symbols *)
 let makeValidSymbolName (s: string) = 
-  let s = String.copy s in (* So that we can update in place *)
+  let b = Bytes.copy (Bytes.of_string s) in (* So that we can update in place *)
   let l = String.length s in
   for i = 0 to l - 1 do
     let c = String.get s i in
@@ -5090,9 +5090,9 @@ let makeValidSymbolName (s: string) =
       | _ -> false
     in
     if isinvalid then 
-      String.set s i '_';
+      Bytes.set b i '_';
   done;
-  s
+  Bytes.to_string b
 
 let rec addOffset (toadd: offset) (off: offset) : offset =
   match off with

src/ocamlutil/errormsg.ml

@@ -211,16 +211,17 @@ let cleanFileName str =
     if str <> "" && String.get str 0 = '"' (* '"' ( *) 
     then rem_quotes str else str in
   let l = String.length str1 in
+  let str1 = Bytes.of_string str1 in
   let rec loop (copyto: int) (i: int) = 
     if i >= l then 
-      String.sub str1 0 copyto
+      Bytes.to_string (Bytes.sub str1 0 copyto)
      else 
-       let c = String.get str1 i in
+       let c = Bytes.get str1 i in
        if c <> '\\' then begin
-          String.set str1 copyto c; loop (copyto + 1) (i + 1)
+          Bytes.set str1 copyto c; loop (copyto + 1) (i + 1)
        end else begin
-          String.set str1 copyto '/';
-          if i < l - 2 && String.get str1 (i + 1) = '\\' then
+          Bytes.set str1 copyto '/';
+          if i < l - 2 && Bytes.get str1 (i + 1) = '\\' then
               loop (copyto + 1) (i + 2)
           else 
               loop (copyto + 1) (i + 1)

src/ocamlutil/pretty.ml

@@ -725,31 +725,31 @@ let gprintf (finish : doc -> 'b)
               invalid_arg ("dprintf: unimplemented format " 
 			   ^ (String.sub format i (j-i+1)));
 	    let j' = succ j in (* eat the d,i,x etc. *)
-	    let format_spec = "% " in
-	    String.set format_spec 1 (fget j'); (* format_spec = "%x", etc. *)
+	    let format_spec = Bytes.of_string "% " in
+	    Bytes.set format_spec 1 (fget j'); (* format_spec = "%x", etc. *)
             Obj.magic(fun n ->
               collect (dctext1 acc
-                         (Int64.format format_spec n))
+                         (Int64.format (Bytes.to_string format_spec) n))
                 (succ j'))
 	| 'l' ->
 	    if j != i + 1 then invalid_arg ("dprintf: unimplemented format " 
 					    ^ (String.sub format i (j-i+1)));
 	    let j' = succ j in (* eat the d,i,x etc. *)
-	    let format_spec = "% " in
-	    String.set format_spec 1 (fget j'); (* format_spec = "%x", etc. *)
+	    let format_spec = Bytes.of_string "% " in
+	    Bytes.set format_spec 1 (fget j'); (* format_spec = "%x", etc. *)
             Obj.magic(fun n ->
               collect (dctext1 acc
-                         (Int32.format format_spec n))
+                         (Int32.format (Bytes.to_string format_spec) n))
                 (succ j'))
 	| 'n' ->
 	    if j != i + 1 then invalid_arg ("dprintf: unimplemented format " 
 					    ^ (String.sub format i (j-i+1)));
 	    let j' = succ j in (* eat the d,i,x etc. *)
-	    let format_spec = "% " in
-	    String.set format_spec 1 (fget j'); (* format_spec = "%x", etc. *)
+	    let format_spec = Bytes.of_string "% " in
+	    Bytes.set format_spec 1 (fget j'); (* format_spec = "%x", etc. *)
             Obj.magic(fun n ->
               collect (dctext1 acc
-                         (Nativeint.format format_spec n))
+                         (Nativeint.format (Bytes.to_string format_spec) n))
                 (succ j'))
         | 'f' | 'e' | 'E' | 'g' | 'G' ->
             Obj.magic(fun f ->