ssa: closure use org signature

[visualfc]

• ssa: cvtFunc keep signature org variadic. ( toLLVMFunc variadic by NameValist )
• ssa: cvtClosure remove closureCtx param
• internal/abi: fix abi.Type.NumMethod
• internal/lib/reflect: call variadic check

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 95.55%. Comparing base (bab5c05) to head (8fb0dfa). Report is 5 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #880 +/- ## ======================================= Coverage 95.54% 95.55% ======================================= Files 22 22 Lines 6246 6251 +5 ======================================= + Hits 5968 5973 +5 Misses 246 246 Partials 32 32 ```

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