Remove empty non-virtual destructors

While this practice didn't matter too much in C++03, it becomes a
pessimization with the introduction of C++11 move semantics. When
a destructor is defined, no matter how trivial it is, it implicitly
disables move semantics. Because the compiler can sometimes move
objects without the programmer asking, the inability to make these
moves can unnecessarily slow down SFML programs. Removing these
trivial destructors is an easy way to enable move semantics for
more SFML types and quietly speed up everyone's code.

src/SFML/Graphics/Font.cpp

@@ -130,10 +130,7 @@ m_pixelBuffer(copy.m_pixelBuffer)
 
 
 ////////////////////////////////////////////////////////////
-Font::~Font()
-{
-    cleanup();
-}
+Font::~Font() = default;
 
 
 ////////////////////////////////////////////////////////////

src/SFML/Graphics/ImageLoader.cpp

@@ -90,13 +90,6 @@ ImageLoader::ImageLoader()
 }
 
 
-////////////////////////////////////////////////////////////
-ImageLoader::~ImageLoader()
-{
-    // Nothing to do
-}
-
-
 ////////////////////////////////////////////////////////////
 bool ImageLoader::loadImageFromFile(const std::filesystem::path& filename, std::vector<Uint8>& pixels, Vector2u& size)
 {

src/SFML/Graphics/ImageLoader.hpp

@@ -127,12 +127,6 @@ private:
     ////////////////////////////////////////////////////////////
     ImageLoader();
 
-    ////////////////////////////////////////////////////////////
-    /// \brief Destructor
-    ///
-    ////////////////////////////////////////////////////////////
-    ~ImageLoader();
-
     ////////////////////////////////////////////////////////////
     /// \brief Deleted copy constructor
     ///

src/SFML/Window/Android/CursorImpl.cpp

@@ -39,13 +39,6 @@ CursorImpl::CursorImpl()
 }
 
 
-////////////////////////////////////////////////////////////
-CursorImpl::~CursorImpl()
-{
-    // Nothing.
-}
-
-
 ////////////////////////////////////////////////////////////
 bool CursorImpl::loadFromPixels(const Uint8* /* pixels */, Vector2u /* size */, Vector2u /* hotspot */)
 {

src/SFML/Window/Android/CursorImpl.hpp

@@ -55,14 +55,6 @@ public:
     ////////////////////////////////////////////////////////////
     CursorImpl();
 
-    ////////////////////////////////////////////////////////////
-    /// \brief Destructor
-    ///
-    /// Refer to sf::Cursor::~Cursor().
-    ///
-    ////////////////////////////////////////////////////////////
-    ~CursorImpl();
-
     ////////////////////////////////////////////////////////////
     /// \brief Deleted copy constructor
     ///

src/SFML/Window/DRM/CursorImpl.cpp

@@ -39,12 +39,6 @@ CursorImpl::CursorImpl()
 }
 
 
-////////////////////////////////////////////////////////////
-CursorImpl::~CursorImpl()
-{
-}
-
-
 ////////////////////////////////////////////////////////////
 bool CursorImpl::loadFromPixels(const Uint8* /*pixels*/, Vector2u /*size*/, Vector2u /*hotspot*/)
 {

src/SFML/Window/DRM/CursorImpl.hpp

@@ -53,14 +53,6 @@ public:
     ////////////////////////////////////////////////////////////
     CursorImpl();
 
-    ////////////////////////////////////////////////////////////
-    /// \brief Destructor
-    ///
-    /// Refer to sf::Cursor::~Cursor().
-    ///
-    ////////////////////////////////////////////////////////////
-    ~CursorImpl();
-
     ////////////////////////////////////////////////////////////
     /// \brief Deleted copy constructor
     ///

src/SFML/Window/iOS/CursorImpl.cpp

@@ -39,13 +39,6 @@ CursorImpl::CursorImpl()
 }
 
 
-////////////////////////////////////////////////////////////
-CursorImpl::~CursorImpl()
-{
-    // Nothing.
-}
-
-
 ////////////////////////////////////////////////////////////
 bool CursorImpl::loadFromPixels(const Uint8* /* pixels */, Vector2u /* size */, Vector2u /* hotspot */)
 {

src/SFML/Window/iOS/CursorImpl.hpp

@@ -55,14 +55,6 @@ public:
     ////////////////////////////////////////////////////////////
     CursorImpl();
 
-    ////////////////////////////////////////////////////////////
-    /// \brief Destructor
-    ///
-    /// Refer to sf::Cursor::~Cursor().
-    ///
-    ////////////////////////////////////////////////////////////
-    ~CursorImpl();
-
     ////////////////////////////////////////////////////////////
     /// \brief Deleted copy constructor
     ///