Make it compile on Debian/GCC 4.7
Breaking line
Merge pull request #99 from caiosba/master

Make it compile on Debian/GCC 4.7
Don't care about signed/unsigned compare

Summary:
We need to stop these:
https://github.com/facebook/rocksdb/pull/99
https://github.com/facebook/rocksdb/pull/83

Test Plan: no

Reviewers: dhruba, haobo, sdong, ljin, yhchiang

Reviewed By: ljin

CC: leveldb

Differential Revision: https://reviews.facebook.net/D16905
Fix a bug that Prev() can hang.

Summary: Prev() now can hang when there is a key with more than max_skipped number of appearance internally but all of them are newer than the sequence ID to seek. Add unit tests to confirm the bug and fix it.

Test Plan: make all check

Reviewers: igor, haobo

Reviewed By: igor

CC: ljin, yhchiang, leveldb

Differential Revision: https://reviews.facebook.net/D16899
No prefix iterator in db_stress

Summary: We're trying to deprecate prefix iterators, so no need to test them in db_stress

Test Plan: ran it

Reviewers: ljin

Reviewed By: ljin

CC: leveldb

Differential Revision: https://reviews.facebook.net/D16917