renderer/native: Don't close DMA buf fds before handing them forward

We closed all the DMA buffer fds after creating the DMA buffer backed
CoglFramebuffer, which meant that the fds we passed to CoglDmaBufHandle
were already closed. This broke screen casting with DMA buffers.

Fixes: 8509b74532 ("Make DMA buffer allocation format and modifier aware")
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4177>

src/backends/native/meta-renderer-native.c

@@ -1089,11 +1089,11 @@ meta_renderer_native_create_dma_buf (CoglRenderer     *cogl_renderer,
                                                            offsets,
                                                            plane_modifiers,
                                                            error);
-
-        close_fds (fds, n_planes);
-
         if (!dmabuf_fb)
-          return NULL;
+          {
+            close_fds (fds, n_planes);
+            return NULL;
+          }
 
         dmabuf_handle =
           cogl_dma_buf_handle_new (dmabuf_fb,