Slightly improve int32 decoding performance
Slightly improve int32 decoding performance

jbboehr/MaxMind-DB-Reader-php,maxmind/MaxMind-DB-Reader-php,maxmind/MaxMind-DB-Reader-php,maxmind/MaxMind-DB-Reader-php,jbboehr/MaxMind-DB-Reader-php,jbboehr/MaxMind-DB-Reader-php