cmake: Minor cleanups in X11 platform CMakeLists.txt

plugins/platforms/x11/standalone/CMakeLists.txt

@@ -18,21 +18,18 @@ set(X11PLATFORM_SOURCES
     xfixes_cursor_event_filter.cpp
 )
 
-if (X11_Xinput_FOUND)
-    set(X11PLATFORM_SOURCES ${X11PLATFORM_SOURCES} xinputintegration.cpp)
-endif()
-
-if (HAVE_EPOXY_GLX)
-    set(X11PLATFORM_SOURCES ${X11PLATFORM_SOURCES} glxbackend.cpp glx_context_attribute_builder.cpp)
-endif()
-
 add_library(KWinX11Platform MODULE ${X11PLATFORM_SOURCES})
 set_target_properties(KWinX11Platform PROPERTIES LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/bin/org.kde.kwin.platforms/")
 target_link_libraries(KWinX11Platform eglx11common kwin kwinxrenderutils SceneOpenGLBackend VsyncSupport Qt5::X11Extras XCB::CURSOR KF5::Crash X11::X11)
 if (X11_Xi_FOUND)
+    target_sources(KWinX11Platform PRIVATE xinputintegration.cpp)
     target_link_libraries(KWinX11Platform X11::Xi)
 endif()
 
+if (HAVE_EPOXY_GLX)
+    target_sources(KWinX11Platform PRIVATE glxbackend glx_context_attribute_builder.cpp)
+endif()
+
 if (KWIN_BUILD_XRENDER_COMPOSITING)
     target_sources(KWinX11Platform PRIVATE x11xrenderbackend.cpp)
     target_link_libraries(KWinX11Platform SceneXRenderBackend)