backend/drm: avoid creating empty FB_DAMAGE_CLIPS prop
drmModeCreatePropertyBlob cannot create zero-sized blobs, that
fails with EINVAL.
Closes:
@@ -201,6 +201,7 @@ static bool atomic_crtc_commit(struct wlr_drm_connector *conn,
uint32_t fb_damage_clips = 0;
if ((state->base->committed & WLR_OUTPUT_STATE_DAMAGE) &&
+ pixman_region32_not_empty((pixman_region32_t *)&state->base->damage) &&
crtc->primary->props.fb_damage_clips != 0) {
int rects_len;
const pixman_box32_t *rects = pixman_region32_rectangles(
