dri: add queryCompatibleRenderOnlyDeviceFd() to __DRI_MESA extension

With this change we are able to query the render node fd of a
render-only device compatible with a given KMS-only device (at the
egl/dri2 level).

It uses pipe_loader_get_compatible_render_capable_device_fd(), which was
added in commit "pipe-loader: add
pipe_loader_get_compatible_render_capable_device_fd()".

Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>
Reviewed-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24825>

include/GL/internal/mesa_interface.h

@@ -61,6 +61,8 @@ struct __DRImesaCoreExtensionRec {
 
    /* driver function for finishing initialization inside createNewScreen(). */
    const __DRIconfig **(*initScreen)(struct dri_screen *screen);
+
+   int (*queryCompatibleRenderOnlyDeviceFd)(int kms_only_fd);
 };
 
 #endif /* MESA_INTERFACE_H */

src/gallium/frontends/dri/dri2.c

@@ -2477,12 +2477,19 @@ fail:
    return NULL;
 }
 
+static int
+dri_query_compatible_render_only_device_fd(int kms_only_fd)
+{
+   return pipe_loader_get_compatible_render_capable_device_fd(kms_only_fd);
+}
+
 static const struct __DRImesaCoreExtensionRec mesaCoreExtension = {
    .base = { __DRI_MESA, 1 },
    .version_string = MESA_INTERFACE_VERSION_STRING,
    .createNewScreen = driCreateNewScreen2,
    .createContext = driCreateContextAttribs,
    .initScreen = dri2_init_screen,
+   .queryCompatibleRenderOnlyDeviceFd = dri_query_compatible_render_only_device_fd,
 };
 
 /* This is the table of extensions that the loader will dlsym() for. */