vector: make some more options override-able
vector: make some more options override-able

Unfortunately, buildRustPackage isn't very flexible right now, and most
of these attrs can't be overridden. This is needed for some general
patch work, but isn't really long term sustainable. I plan on reverting
this after Vector 0.6 is out.

Signed-off-by: Austin Seipp <48c905ac3851f382b914247d97dd93273d5ff555@pobox.com>

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs