Replace switch statement in sa2addrlist() with memory-efficient lookup table
following mruby's memory-first design philosophy. Uses compact structure with
only valid address family entries instead of wasteful 256-entry array.
Changes:
- Add af_info_t structure for address family metadata
- Create compact af_table[] with only valid entries (~6-8 families)
- Replace manual switch with get_af_info() linear search lookup
- Support platform-specific families (AF_UNIX, AF_LOCAL, AF_LINK, etc.)
- Use offset-based port extraction for better performance
Performance characteristics:
- O(n) linear search where n=6-8 (negligible vs switch statement)
- Eliminates branch prediction overhead
- Easier addition of new address families
- Consistent optimization pattern following mruby memory priority
Co-Authored-By: Claude <noreply@anthropic.com>
Yukihiro "Matz" Matsumoto
80a2183b46