Specify make targets explicitly in nix package

The umu-vendored make target depends on git submodules and is not needed
now that we provide pyzstd as a nix package.

Until now, it was disabled with a patch, however that broke in #330.

Instead of patching the makefile's `all` target, we can explicitly
specify the targets we want to build/install using make flags.

This is a temporary workaround until the Makefile can automatically
disable the target when the dependency is already available. Maybe a
make variable?

That said, having the install targets listed explicitly allows the
`delta` targets to be conditional on `withDeltaUpdates`.

packaging/nix/unwrapped.nix

@@ -19,13 +19,33 @@ umu-launcher-unwrapped.overridePythonAttrs (prev: {
   #   https://github.com/Open-Wine-Components/umu-launcher/pull/289
   # - The other is backporting:
   #   https://github.com/Open-Wine-Components/umu-launcher/pull/343
-  patches = [
-    # Remove `umu-vendored` from the `all` target
-    # This causes an error when building vendored dependencies:
-    # python3 -m pip install urllib3 -t builddir
-    # => No module named pip
-    ./0-Makefile-no-vendor.patch
-  ];
+  patches = [];
+
+  # The `umu-vendored` target needs submodules. However, we don't actually need
+  # this target or those submodules anyway, since we add `pyzstd` as a nix package
+  #
+  # As a temporary solution, we explicitly specify the supported build targets:
+  buildFlags =
+    (prev.buildFlags or [])
+    ++ [
+      "umu-dist"
+      "umu-launcher"
+    ];
+
+  # Same issue for install targets
+  installTargets =
+    (prev.installTargets or [])
+    ++ [
+      "umu-dist"
+      "umu-docs"
+      "umu-launcher"
+      "umu-install"
+      "umu-launcher-install"
+    ]
+    ++ lib.optionals withDeltaUpdates [
+      "umu-delta"
+      "umu-delta-install"
+    ];
 
   nativeBuildInputs =
     (prev.nativeBuildInputs or [])