Summary:
Make rocksdb build on macos:
1) Reorganize OS-specific flags and deps in rocksdb/src/TARGETS
2) Sandbox fbcode apple platform builds from repo root include path (which conflicts
with layout of rocksdb headers).
3) Fix dep-translation for bzip2.
Reviewed By: andrewjcg
Differential Revision: D15125826
fbshipit-source-id: 8e143c689b88b5727e54881a5e80500f879a320b