Nix: Add dev shell for building using vcpkg

flake.nix

@@ -65,9 +65,28 @@
       apps.default = flake-utils.lib.mkApp {
         drv = self.packages.${system}.default;
       };
-      devShells.default = pkgs.mkShell {
+      devShells = {
+        default = pkgs.mkShell {
           inputsFrom = [ self.packages.${system}.default ];
         };
+
+        # Shell for building static melonDS release builds with vcpkg
+        # Use mkShellNoCC to ensure Nix's gcc/clang and stdlib isn't used
+        vcpkg = pkgs.mkShellNoCC {
+          packages = with pkgs; [
+            autoconf
+            autoconf-archive
+            automake
+            cmake
+            cups.dev # Needed by qtbase despite not enabling print support
+            git
+            iconv.dev
+            libtool
+            ninja
+            pkg-config
+          ];
+        };
+      };
     }
   );
 }