fix(flake): add debuginfo to nvim-debug (#13947)

nvim-debug was missing symbols.
adding the lock file to remove the flake warning message as well.

contrib/flake.lock

@@ -0,0 +1,43 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1610051610,
+        "narHash": "sha256-U9rPz/usA1/Aohhk7Cmc2gBrEEKRzcW4nwPWMPwja4Y=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "3982c9903e93927c2164caa727cd3f6a0e6d14cc",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1613226215,
+        "narHash": "sha256-3rA5cGIrBHD6yeKhNhsF7/t461ww25oJY8KyBb0IhjU=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "ff96a0fa5635770390b184ae74debea75c3fd534",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

contrib/flake.nix

@@ -27,15 +27,20 @@
           });
 
           # a development binary to help debug issues
-          neovim-debug = (neovim.override {
-            stdenv = if pkgs.stdenv.isLinux then pkgs.llvmPackages_latest.stdenv else pkgs.stdenv;
+          neovim-debug = let
+            stdenv = pkgs.stdenvAdapters.keepDebugInfo (if pkgs.stdenv.isLinux then pkgs.llvmPackages_latest.stdenv else pkgs.stdenv);
+          in
+            pkgs.enableDebugging ((neovim.override {
             lua = pkgs.enableDebugging pkgs.luajit;
+            inherit stdenv;
           }).overrideAttrs (oa: {
             cmakeBuildType = "Debug";
             cmakeFlags = oa.cmakeFlags ++ [
               "-DMIN_LOG_LEVEL=0"
             ];
-          });
+
+            disallowedReferences = [];
+          }));
 
           # for neovim developers, very slow
           # brings development tools as well