a/vk: Add function to check timeline semaphore import/export cap

src/xrt/auxiliary/vk/vk_helpers.h

@@ -1148,6 +1148,15 @@ vk_csci_get_image_external_handle_type(struct vk_bundle *vk);
  *
  */
 
+/*!
+ * Is there a good likelihood that the import/export of a timeline semaphore
+ * will succeed, in other words will the below functions work.
+ *
+ * @ingroup aux_vk
+ */
+XRT_CHECK_RESULT bool
+vk_can_import_and_export_timeline_semaphore(struct vk_bundle *vk);
+
 /*!
  * @brief Creates a Vulkan fence, submits it to the default VkQueue and return
  * its native graphics sync handle.

src/xrt/auxiliary/vk/vk_sync_objects.c

@@ -61,6 +61,34 @@ vk_get_timeline_semaphore_handle_type(struct vk_bundle *vk)
 #endif
 
 
+/*
+ *
+ * Check functions.
+ *
+ */
+
+bool
+vk_can_import_and_export_timeline_semaphore(struct vk_bundle *vk)
+{
+#ifdef VK_KHR_timeline_semaphore
+	// Timeline semaphore extension and feature been enabled?
+	if (!vk->features.timeline_semaphore) {
+		return false;
+	}
+
+	// Supported handle type for import/export?
+	if (vk_get_timeline_semaphore_handle_type(vk) == 0) {
+		return false;
+	}
+
+	// Everything points to yes!
+	return true;
+#else
+	return false;
+#endif
+}
+
+
 /*
  *
  * Export.