ZJIT: Fix block_param_proxy_not_iseq_or_ifunc exits

[k0kubun]

On lobsters, block_param_proxy_not_iseq_or_ifunc seems like the 4th (counting both compile_error_register_spill_on_* as 1st) most frequent exits.

We need to:

1. Add stats to break down the types of block params to be supported
   • We need to add zjit_profile = true to getblockparamproxy, and profile block_handler for that instruction.
2. Fix unsupported block params
   • I suspect a lot of them are &nil, which is to be confirmed by (1).