Summary:
test the `DBOptions(const Options&)` and `ColumnFamilyOptions(const Options&)` constructors. Actually this'll work better once we refactor `RandomInitDBOptions` / `RandomInitCFOptions` to use the authoritative sources of struct members: `db_options_type_info` / `cf_options_type_info` (internal task T21804189 for this).
Closes https://github.com/facebook/rocksdb/pull/2873
Differential Revision: D5817141
Pulled By: ajkr
fbshipit-source-id: 8567c20feced9d1751fdf1f4383e2af30f7e3591