fix a bug in RTDiskPostingReader::decodeNext() decoding term positions, when growing position buffer size, use "while" to ensure the buffer size is large enough.
fix a bug in RTDiskPostingReader::decodeNext() decoding term positions,
when growing position buffer size, use "while" to ensure the buffer size
is large enough.

pombredanne/izenelib,pombredanne/izenelib,pombredanne/izenelib,izenecloud/izenelib,pombredanne/izenelib,izenecloud/izenelib,izenecloud/izenelib,izenecloud/izenelib