Clang fixes for friend declarations.

Friending only constructor apparently doesn't help, specifying
full-scope name for Resource.

src/ResourceManager.h

@@ -89,7 +89,7 @@ namespace Implementation {
     };
 
     template<class T> class ResourceManagerData {
-        template<class, class> friend class Resource;
+        template<class, class> friend class Magnum::Resource;
         friend class AbstractResourceLoader<T>;
 
         ResourceManagerData(const ResourceManagerData<T>&) = delete;

src/SceneGraph/AbstractObject.h

@@ -55,7 +55,7 @@ template<std::uint8_t dimensions, class T = GLfloat> class AbstractObject
 {
     friend class Corrade::Containers::LinkedList<AbstractFeature<dimensions, T>>;
     friend class Corrade::Containers::LinkedListItem<AbstractFeature<dimensions, T>, AbstractObject<dimensions, T>>;
-    friend AbstractFeature<dimensions, T>::AbstractFeature(AbstractObject<dimensions, T>*);
+    friend class AbstractFeature<dimensions, T>;
 
     public:
         /** @brief Feature object type */