py: Change nlr_jump to nlr_raise, to aid in debugging.

This does not affect code size or performance when debugging turned off.

To address issue #420.
diff --git a/py/objint_longlong.c b/py/objint_longlong.c
index f4a65ce..02389d6 100644
--- a/py/objint_longlong.c
+++ b/py/objint_longlong.c
@@ -144,7 +144,7 @@
     // TODO: this doesn't handle Python hacked 0o octal syntax
     v = strtoll(s, &end, 0);
     if (*end != 0) {
-        nlr_jump(mp_obj_new_exception_msg(&mp_type_SyntaxError, "invalid syntax for number"));
+        nlr_raise(mp_obj_new_exception_msg(&mp_type_SyntaxError, "invalid syntax for number"));
     }
     mp_obj_int_t *o = m_new_obj(mp_obj_int_t);
     o->base.type = &mp_type_int;