Clean up Wayland resources on wxGLCanvas destructor

If the wxGLCanvas is destroyed immediately (without hiding it first),
the GTKs widget's `unmap` signal which usually destroys the Wayland
resources is not emitted. Thus, we need to ensure they are destroyed
on the destructor instead.

This fixes an use-after-free issue, sometimes causing a crash, because
one of the leaked resources is the canvas's Wayland frame callback.

See wxWidgets#24013, wxWidgets#24016.

(cherry picked from commit 22ae7a5)

Author: joanbm

src/unix/glegl.cpp

@@ -630,6 +630,7 @@ wxGLCanvasEGL::~wxGLCanvasEGL()
     if ( m_surface )
         eglDestroySurface(m_display, m_surface);
 #ifdef GDK_WINDOWING_WAYLAND
+    DestroyWaylandSubsurface();
     g_clear_pointer(&m_wlEGLWindow, wl_egl_window_destroy);
     g_clear_pointer(&m_wlSurface, wl_surface_destroy);