Simplify backtrace mechanism; fix #3633 #3634 #3644

Instead of preserving a backtrace in `mrb_state`, `mrb_exc_set`
keeps packed backtrace in an exception object. `#backtrace` unpacks
it to an array of strings.

1 files changed, 0 insertions, 2 deletions

diff --git a/src/vm.c b/src/vm.c
index b56da6c88..896be7ad9 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -1741,8 +1741,6 @@ RETRY_TRY_BLOCK:
 
       L_RAISE:
         ci0 = ci = mrb->c->ci;
-        mrb_obj_iv_ifnone(mrb, mrb->exc, mrb_intern_lit(mrb, "lastpc"), mrb_cptr_value(mrb, pc));
-        mrb_obj_iv_ifnone(mrb, mrb->exc, mrb_intern_lit(mrb, "ciidx"), mrb_fixnum_value(ci - mrb->c->cibase));
         eidx = ci->eidx;
         if (ci == mrb->c->cibase) {
           if (ci->ridx == 0) goto L_STOP;