Update for modular build

py2app requires AppKit, so it needs at least `dev_gui_common`.

Author: facekapow

CMakeLists.txt

@@ -76,7 +76,9 @@ add_subdirectory(Modules/six-1.12.0/six-1.12.0)
 add_subdirectory(Modules/macholib-1.5.1/macholib-1.5.1)
 add_subdirectory(Modules/xattr-0.6.4/xattr-0.6.4)
 add_subdirectory(Modules/setuptools-41.0.1/setuptools-41.0.1)
-add_subdirectory(Modules/py2app-0.7.3/py2app-0.7.3-noprebuilt)
+if (COMPONENT_dev_gui_common)
+	add_subdirectory(Modules/py2app-0.7.3/py2app-0.7.3-noprebuilt)
+endif()
 add_subdirectory(Modules/altgraph-0.10.2/altgraph-0.10.2)
 add_subdirectory(Modules/modulegraph-0.10.4/modulegraph-0.10.4)