Consider re-exporting rocksdb crate from store

[matklad]

#6300 made me realize that we specify version of rocks we use in several places. This is a bit subomtimal. In the store/lib.rs we might want to add pub extern crate rocksdb; to have the version specified in just one Cargo.toml

[mina86]

I don’t know if this is really an issue. Yes, we need to update the version in three places but that’s hardly a large number. Indexer uses rocksdb directly because it creates its own database unrelated to store. runtime-params-estimator uses the crate to bypass all of the abstraction. It doesn’t feel right to export rocksdb through store just to facilitate easy abstraction layer breaking.

[matklad]

Yeah, that's a valid point. I guess I could argue a bit that exposing just the crate (as opposed to as_rocks method) doesn't really break abstraction, but that's not a super-strong argument. But for me, on balance, one place to set version/flags of the crate feels more important than abstraction purity at this case.

There's also rust-lang/cargo#10497 which presumably would allow us to fix this in a more principled way in a near future?