Fix "undefined symbol: __cxa_pure_virtual" error on load.
Fix "undefined symbol: __cxa_pure_virtual" error on load.

wmorgan/leveldb-ruby,wmorgan/leveldb-ruby,assispedro/leveldb-ruby,assispedro/leveldb-ruby,wmorgan/leveldb-ruby,assispedro/leveldb-ruby,assispedro/leveldb-ruby,wmorgan/leveldb-ruby