Use type tag for hash code in ht_hash_func()

The function corresponding to `ht_hash_func()` was as follows in the days of
khash implementation (before d78acc7a).

  ```c
  mrb_hash_ht_hash_func(mrb_state *mrb, mrb_value key)
  {
    enum mrb_vtype t = mrb_type(key);
    ...
    switch (t) {
    ...
    default:
      hv = mrb_funcall(mrb, key, "hash", 0);
      h = (khint_t)t ^ (khint_t)mrb_fixnum(hv);
      break;
    }
    ...
  }
  ```

When switched to the segmented list implementation (d78acc7a), this function
was changed as follows.

  ```c
  sg_hash_func(mrb_state *mrb, seglist *t, mrb_value key)
  {
    enum mrb_vtype tt = mrb_type(key);
    ...
    switch (tt) {
    ...
    default:
      hv = mrb_funcall(mrb, key, "hash", 0);
      h = (size_t)t ^ (size_t)mrb_fixnum(hv);
      break;
    }
    ...
  }
  ```

Since the argument `t` was added, the variable for type tag was changed from
`t` to `tt`, but the variable used in the expression of `h` remained `t`.

Probably this is an omission of change, so fixed it.

include/mruby/proc.h

@@ -34,7 +34,7 @@ struct REnv {
 #define MRB_ENV_HEAP_P(e) ((e)->flags & MRB_ENV_HEAPED)
 #define MRB_ENV_ONSTACK_P(e) (((e)->flags & MRB_ENV_CLOSED) == 0)
 #define MRB_ENV_BIDX(e) (((e)->flags >> 8) & 0xff)
-#define MRB_ENV_SET_BIDX(e,idx) ((e)->flags = (((e)->flags & ~(0xff<<8))|((unsigned int)(idx) & 0xff)<<10))
+#define MRB_ENV_SET_BIDX(e,idx) ((e)->flags = (((e)->flags & ~(0xff<<8))|((unsigned int)(idx) & 0xff)<<8))
 
 void mrb_env_unshare(mrb_state*, struct REnv*);
 

src/hash.c

@@ -73,7 +73,7 @@ ht_hash_func(mrb_state *mrb, htable *t, mrb_value key)
 
   default:
     hv = mrb_funcall(mrb, key, "hash", 0);
-    h = (size_t)t ^ (size_t)mrb_fixnum(hv);
+    h = (size_t)tt ^ (size_t)mrb_fixnum(hv);
     break;
   }
   if (index && (index != t->index || capa != index->capa)) {

src/vm.c

@@ -754,16 +754,25 @@ mrb_yield_with_class(mrb_state *mrb, mrb_value b, mrb_int argc, const mrb_value
   ci = cipush(mrb);
   ci->mid = mid;
   ci->proc = p;
-  ci->stackent = mrb->c->stack;
-  ci->argc = (int)argc;
   ci->target_class = c;
   ci->acc = CI_ACC_SKIP;
-  n = MRB_PROC_CFUNC_P(p) ? (int)(argc+2) : p->body.irep->nregs;
-  mrb->c->stack = mrb->c->stack + n;
+  ci->stackent = mrb->c->stack;
+  mrb->c->stack += n;
+  if (argc >= CALL_MAXARGS) {
+    ci->argc = -1;
+    n = 3;
+  }
+  else {
+    ci->argc = (int)argc;
+    n = argc + 2;
+  }
   mrb_stack_extend(mrb, n);
-
   mrb->c->stack[0] = self;
-  if (argc > 0) {
+  if (ci->argc < 0) {
+    mrb->c->stack[1] = mrb_ary_new_from_values(mrb, argc, argv);
+    argc = 1;
+  }
+  else if (argc > 0) {
     stack_copy(mrb->c->stack+1, argv, argc);
   }
   mrb->c->stack[argc+1] = mrb_nil_value();

test/t/kernel.rb

@@ -116,6 +116,13 @@ assert('Kernel#block_given?', '15.3.1.3.6') do
       "block"
     end
   end
+
+  def bg_try_in_block
+    -> { block_given? }[]
+  end
+
+  assert_false bg_try_in_block
+  assert_true bg_try_in_block{}
 end
 
 assert('Kernel#class', '15.3.1.3.7') do