Build: Switch to CMake :^)

Closes https://github.com/SerenityOS/serenity/issues/2080

Services/WindowServer/CMakeLists.txt

@@ -0,0 +1,27 @@
+compile_ipc(WindowServer.ipc WindowServerEndpoint.h)
+compile_ipc(WindowClient.ipc WindowClientEndpoint.h)
+
+set(SOURCES
+    AppletManager.cpp
+    Button.cpp
+    ClientConnection.cpp
+    Clipboard.cpp
+    Compositor.cpp
+    Cursor.cpp
+    EventLoop.cpp
+    main.cpp
+    MenuBar.cpp
+    Menu.cpp
+    MenuItem.cpp
+    MenuManager.cpp
+    Screen.cpp
+    Window.cpp
+    WindowFrame.cpp
+    WindowManager.cpp
+    WindowSwitcher.cpp
+    WindowServerEndpoint.h
+    WindowClientEndpoint.h
+)
+
+serenity_bin(WindowServer)
+target_link_libraries(WindowServer LibCore LibGfx LibThread LibPthread LibIPC)