gnvim: fix build
gnvim: fix build

When running the default builder for Rust, the artifacts would be stored
in `target/<arch>/<profile>`, however the `install`-target expects the
default structure (`target/<profile>`) of `cargo`-builds.

When using the Makefile for building as well, the expected structure is
created instead.

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