Contain retained OpenGL runtime sources

cmake/PanoPainterSources.cmake

@@ -9,19 +9,22 @@ set(PP_LEGACY_ENGINE_SOURCES
     src/canvas_actions.cpp
     src/canvas_layer.cpp
     src/event.cpp
-    src/font.cpp
     src/hmd.cpp
     src/image.cpp
     src/log.cpp
     src/mp4enc.cpp
-    src/rtt.cpp
     src/serializer.cpp
     src/settings.cpp
+    src/util.cpp
+    src/wacom.cpp
+)
+
+set(PP_LEGACY_RENDERER_GL_SOURCES
+    src/font.cpp
+    src/rtt.cpp
     src/shader.cpp
     src/shape.cpp
     src/texture.cpp
-    src/util.cpp
-    src/wacom.cpp
 )
 
 set(PP_LEGACY_APP_SOURCES