gtk4: Try importing dmabufs withouth DMA_DRM caps

If an upstream elements uses dmabufs - and supports the videometa -
but negotiated sysmem caps, try to use the dmabuf texture builder
for direct GPU buffer imports.

This is notably the case if a udmabuf allocator is used, but also
if elements support dmabufs but do not yet support the DMA_DRM API.
An example for the later is Snapshot on phones. On one hand its
current implementation around camerabin makes using DMA_DRM caps hard
without breaking capturing with software encoders, while on the other
hand importing buffers with GL/VK not only avoids a buffer upload/copy,
but also `DMA_BUF_IOCTL_SYNC` calls, which are potentially expensive
on aarch64. Finally importing dmabufs potentially allows offloading to
display planes.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/2490>

video/gtk4/src/sink/frame.rs

@@ -713,8 +713,20 @@ impl Frame {
                 .peek_memory(0)
                 .is_memory_type::<gst_allocators::DmaBufMemory>()
         {
+            let drm_info;
+            let drm_info_ref = match info.dma_drm() {
+                Some(drm) => Some(drm),
+                None => match gst_video::VideoInfoDmaDrm::from_video_info(info, 0) {
+                    Ok(i) => {
+                        drm_info = Some(i);
+                        drm_info.as_ref()
+                    }
+                    Err(_) => None,
+                },
+            };
+
             if let Some((vmeta, info)) =
-                Option::zip(buffer.meta::<gst_video::VideoMeta>(), info.dma_drm())
+                Option::zip(buffer.meta::<gst_video::VideoMeta>(), drm_info_ref)
             {
                 let mut fds = [-1i32; 4];
                 let mut offsets = [0; 4];