ui/spice: Blit the scanout texture if its memory layout is not linear

In cases where the scanout buffer is provided as a texture (e.g. Virgl)
we need to check to see if it has a linear memory layout or not. If
it doesn't have a linear layout, then blitting it onto the texture
associated with the display surface (which already has a linear layout)
seems to ensure that there is no corruption seen regardless of which
encoder or decoder is used.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Cc: Frediano Ziglio <freddy77@gmail.com>
Cc: Dongwon Kim <dongwon.kim@intel.com>
Cc: Michael Scherle <michael.scherle@rz.uni-freiburg.de>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Message-Id: <20250617043546.1022779-8-vivek.kasireddy@intel.com>

include/ui/spice-display.h

@@ -132,6 +132,9 @@ struct SimpleSpiceDisplay {
     egl_fb guest_fb;
     egl_fb blit_fb;
     egl_fb cursor_fb;
+    bool backing_y_0_top;
+    bool blit_scanout_texture;
+    bool new_scanout_texture;
     bool have_hot;
 #endif
 };