ocamlfind doesn't work for wasicaml

[gerdstolpmann]

three problems:

1. wasicaml has a bug and cannot run executables by non-absolute path (-> solve there, fix: find commands in PATH when the commands were built with wasicaml remixlabs/wasicaml#58)

/Users/gerd/biz/figly/protoquery/wasicaml/bin/ocamlfind ocamlmklib
ocamlfind: Package `threads' not found

This is due to a bug in findlib: frontend.ml, line 923, change this to:

  let type_of_threads =
    try package_property [] "threads" "type_of_threads"
    with No_such_package _ -> "ignore"

3. wasicaml doesn't support Unix.spawn, but you can use Sys.command. Alternate run_command implementation:

let run_command ?filter verbose cmd args =
  let printable_cmd =
    cmd ^ " " ^ String.concat " " (List.map escape_if_needed args) in
  ( match verbose with
      | Normal ->
          ()
      | Verbose ->
          print_endline ("+ " ^ printable_cmd);
          if filter <> None then
            print_string
              ("  (output of this command is filtered by ocamlfind)\n")
      | Only_show ->
          print_endline printable_cmd
  );
  flush stdout;

  if verbose <> Only_show then (
    let temp_file_opt =
      match filter with
        | None -> None
        | Some _ ->
            Some(Filename.temp_file "ocamlfind" ".out") in
    let cmd1 =
      match temp_file_opt with
        | None -> cmd
        | Some f -> cmd ^ " > " ^ Filename.quote f in
    let code =
      Sys.command cmd1 in
    if code <> 0 then (
      if verbose = Verbose then
        print_string (cmd ^ " returned with exit code " ^ string_of_int code ^ "\n");
      exit code
    );

    ( match filter, temp_file_opt with
        | Some filter_fun, Some temp_file ->
            let ch = open_in temp_file in
            ( try
                while true do
                  let line = input_line ch in
                  match filter_fun line with
                      None -> ()       (* Suppress line *)
                    | Some line' -> print_endline line'
                done;
                assert false
              with
                  End_of_file ->
                  close_in ch;
                  flush stdout
            )
        | _ -> ()
    )
  )
;;