Merge pull request #177 from nanwu/master

specify the command to install build_tools/mac-install-gflags.sh file in...
HashLinkList to log distribution of number of entries aross buckets

Summary: Add two parameters of hash linked list to log distribution of number of entries across all buckets, and a sample row when there are too many entries in one single bucket.

Test Plan: Turn it on in plain_table_db_test and see the logs.

Reviewers: haobo, ljin

Reviewed By: ljin

Subscribers: leveldb, nkg-, dhruba, yhchiang

Differential Revision: https://reviews.facebook.net/D19095
Change order of parameters in adaptive table factory

Summary:
This is minor, but if we put the writing talbe factory as the third parameter, when we add a new table format, we'll have a situation:
1) block based factory
2) plain table factory
3) output factory
4) new format factory

I think it makes more sense to have output as the first parameter.

Also, fixed a NewAdaptiveTableFactory() call in unit test

Test Plan: unit test

Reviewers: sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D19119