ui: refactor using a common qemu_pixman_shareable

Use a common shareable type for win32 & unix, and helper functions.
This simplify the code as it avoids a lot of #ifdef'ery.

Note: if it helps review, commits could be reordered to introduce the
common type before introducing shareable memory for unix.

Suggested-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-ID: <20241008125028.1177932-19-marcandre.lureau@redhat.com>

include/ui/surface.h

@@ -23,13 +23,8 @@ typedef struct DisplaySurface {
     GLenum gltype;
     GLuint texture;
 #endif
-#ifdef WIN32
-    HANDLE handle;
-    uint32_t handle_offset;
-#else
-    int shmfd;
-    uint32_t shmfd_offset;
-#endif
+    qemu_pixman_shareable share_handle;
+    uint32_t share_handle_offset;
 } DisplaySurface;
 
 PixelFormat qemu_default_pixelformat(int bpp);
@@ -40,13 +35,10 @@ DisplaySurface *qemu_create_displaysurface_from(int width, int height,
 DisplaySurface *qemu_create_displaysurface_pixman(pixman_image_t *image);
 DisplaySurface *qemu_create_placeholder_surface(int w, int h,
                                                 const char *msg);
-#ifdef WIN32
-void qemu_displaysurface_win32_set_handle(DisplaySurface *surface,
-                                          HANDLE h, uint32_t offset);
-#else
-void qemu_displaysurface_set_shmfd(DisplaySurface *surface,
-                                   int shmfd, uint32_t offset);
-#endif
+
+void qemu_displaysurface_set_share_handle(DisplaySurface *surface,
+                                          qemu_pixman_shareable handle,
+                                          uint32_t offset);
 
 DisplaySurface *qemu_create_displaysurface(int width, int height);
 void qemu_free_displaysurface(DisplaySurface *surface);