Fix Zlib_Compress and Zlib_Uncompress

Fix Zlib_Compress and Zlib_Uncompress

Summary:
Zlib_{Compress,Uncompress} did not handle very small input buffers properly. In addition, they did not call inflate/deflate until Z_STREAM_END was returned; it was possible for them to exit when only Z_OK had returned.

This diff also fixes a bunch of lint errors.

Test Plan: Run make check

Reviewers: dhruba, sheki, haobo

Reviewed By: dhruba

CC: leveldb
Differential Revision: https://reviews.facebook.net/D11301