Git: Ignore result symlink created by nix

This patch adds a default nix which invokes a `callPackage`
to build sources from the current working directory.

To invoke the build run `nix-build`.

Cargo.lock

@@ -2416,8 +2416,6 @@ checksum = "7a66a03ae7c801facd77a29370b4faec201768915ac14a721ba36f20bc9c209b"
 [[package]]
 name = "relm4"
 version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cf0363f92b6a7eefd985b47f27b7ae168dd2fd5cd4013a338c9b111c33744d1f"
 dependencies = [
  "flume",
  "fragile",
@@ -2433,9 +2431,7 @@ dependencies = [
 
 [[package]]
 name = "relm4-components"
-version = "0.9.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fb3d67f2982131c5e6047af4278d8fe750266767e57b58bc15f2e11e190eef36"
+version = "0.9.0"
 dependencies = [
  "once_cell",
  "relm4",
@@ -2445,14 +2441,10 @@ dependencies = [
 [[package]]
 name = "relm4-css"
 version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1d3b924557df1cddc687b60b313c4b76620fdbf0e463afa4b29f67193ccf37f9"
 
 [[package]]
 name = "relm4-macros"
 version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fc5885640821d60062497737dd42fd04248d13c7ecccee620caaa4b210fe9905"
 dependencies = [
  "proc-macro2",
  "quote",

default.nix

@@ -22,7 +22,7 @@
 
     src = nix-gitignore.gitignoreSource [] ./.;
 
-    cargoLock.lockFile = ./Cargo.lock;
+    cargoHash = "sha256-RYXnXQZZV01g65EB66LpltI7K2+O5AoqdECKPin7aDc=";
 
     nativeBuildInputs = [
       pkg-config