Some improvements wrt to plugins

ocaml/fstar-lib/FStar_Compiler_Plugins_Base.ml

@@ -0,0 +1,9 @@
+open Dynlink
+
+exception DynlinkError of string
+
+let dynlink_loadfile (fname:string) : unit =
+  try
+    Dynlink.loadfile fname
+  with Dynlink.Error e ->
+    raise (DynlinkError (Dynlink.error_message e))

ocaml/fstar-lib/FStar_Compiler_Util.ml

@@ -287,6 +287,8 @@ let run_process (id: string) (prog: string) (args: string list) (stdin: string o
   kill_process p;
   s
 
+let system_run (cmd:string) : Z.t = Z.of_int (Sys.command cmd)
+
 type read_result = EOF | SIGINT
 
 let handle_stderr (p:proc) (h : string -> unit) =