[vulkan] Don't create a swap chain if the window size is 0

This can actually happen on win32, and creating a zero-sized swap
chain is illegal.

src/vulkan/vulkan_presenter.cpp

@@ -131,6 +131,12 @@ namespace dxvk::vk {
     m_info.imageExtent  = pickImageExtent(caps, desc.imageExtent);
     m_info.imageCount   = pickImageCount(caps, m_info.presentMode, desc.imageCount);
 
+    if (!m_info.imageExtent.width || !m_info.imageExtent.height) {
+      m_info.imageCount = 0;
+      m_info.format     = { VK_FORMAT_UNDEFINED, VK_COLOR_SPACE_SRGB_NONLINEAR_KHR };
+      return VK_SUCCESS;
+    }
+
     VkSurfaceFullScreenExclusiveInfoEXT fullScreenInfo;
     fullScreenInfo.sType            = VK_STRUCTURE_TYPE_SURFACE_FULL_SCREEN_EXCLUSIVE_INFO_EXT;
     fullScreenInfo.pNext            = nullptr;

src/vulkan/vulkan_presenter.h

@@ -177,6 +177,18 @@ namespace dxvk::vk {
     VkResult recreateSwapChain(
       const PresenterDesc&  desc);
 
+    /**
+     * \brief Checks whether a Vulkan swap chain exists
+     *
+     * On Windows, there are situations where we cannot create
+     * a swap chain as the surface size can reach zero, and no
+     * presentation can be performed.
+     * \returns \c true if the presenter has a swap chain.
+     */
+    bool hasSwapChain() const {
+      return m_swapchain;
+    }
+
   private:
 
     Rc<InstanceFn>    m_vki;