ZJIT: Add stat for `def_type` of send fallbacks (#14533)

I thought about creating a new HIR like `SendWithoutBlockFailedToOptimize` that can carry very specific reasons later. But it'll mean adding it to every branch matching `SendWithoutBlock` and may make code unnecessarily complicated.

So I take the easier path for now:

```
Top-4 send fallback def_types (100.0% of total 21,375,357):
      cfunc: 20,164,487 (94.3%)
  optimized:  1,197,897 ( 5.6%)
    attrset:     12,953 ( 0.1%)
      alias:         20 ( 0.0%)
```

0 files changed, 0 insertions, 0 deletions