Merge pull request #85 from kit-ty-kate/410

Add support for OCaml 4.10

Author: xclerc

src/exn_stubs.c

@@ -1,6 +1,6 @@
+#define CAML_INTERNALS
 #include <caml/mlvalues.h>
-
-extern int caml_backtrace_pos;
+#include <caml/backtrace.h>
 
 CAMLprim value Base_clear_caml_backtrace_pos () {
   caml_backtrace_pos = 0;