databases/leveldb: Clean up

- Bump PORTREVISION for package change

SOVERSION has been added by upstream since 1.22.

Reference:	https://github.com/google/leveldb/commit/37300aa54b8256dd2edfd504942eb2bd20823647
		https://github.com/google/leveldb/commit/09fa8868dbe0cb2701f0560c59ebb63cc17f1271