Allow allocating dynamic bloom, plain table indexes and hash linked list from huge...

Allow allocating dynamic bloom, plain table indexes and hash linked list from huge page TLB

Summary: Add an option to allocate a piece of memory from huge page TLB. Add options to trigger it in dynamic bloom, plain table indexes andhash linked list hash table.

Test Plan: make all check

Reviewers: haobo, ljin

Reviewed By: haobo

CC: nkg-, dhruba, leveldb, igor, yhchiang
Differential Revision: https://reviews.facebook.net/D18357

Conflicts:
	db/plain_table_db_test.cc
	util/options.cc