Vulkan/Wayland: Use old swapchain size if none provided.

vulkan/vulkan_swapchain.cpp

@@ -124,6 +124,9 @@ bool Swapchain::create(unsigned int desired_num_swapchain_images, int new_width,
     else
         num_swapchain_images = desired_num_swapchain_images;
 
+    // If extents aren't reported (Wayland), we have to rely on Wayland to report
+    // the size, so keep current extent.
+    if (surface_capabilities.currentExtent.width != -1)
         extents = surface_capabilities.currentExtent;
 
     uint32_t graphics_queue_index = 0;