GPU: Fix Vulkan indexing error for resolve attachment refs (#13768)

(cherry picked from commit 03b14f5211bcf4c6e7ef150a4ceb387f276d0c19)

src/gpu/vulkan/SDL_gpu_vulkan.c

@@ -6089,7 +6089,6 @@ static VkRenderPass VULKAN_INTERNAL_CreateRenderPass(
         colorAttachmentReferences[colorAttachmentReferenceCount].layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
 
         attachmentDescriptionCount += 1;
-        colorAttachmentReferenceCount += 1;
 
         if (colorTargetInfos[i].store_op == SDL_GPU_STOREOP_RESOLVE || colorTargetInfos[i].store_op == SDL_GPU_STOREOP_RESOLVE_AND_STORE) {
             VulkanTextureContainer *resolveContainer = (VulkanTextureContainer *)colorTargetInfos[i].resolve_texture;
@@ -6104,12 +6103,16 @@ static VkRenderPass VULKAN_INTERNAL_CreateRenderPass(
             attachmentDescriptions[attachmentDescriptionCount].initialLayout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
             attachmentDescriptions[attachmentDescriptionCount].finalLayout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
 
-            resolveReferences[resolveReferenceCount].attachment = attachmentDescriptionCount;
-            resolveReferences[resolveReferenceCount].layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+            resolveReferences[colorAttachmentReferenceCount].attachment = attachmentDescriptionCount;
+            resolveReferences[colorAttachmentReferenceCount].layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
 
             attachmentDescriptionCount += 1;
             resolveReferenceCount += 1;
+        } else {
+            resolveReferences[colorAttachmentReferenceCount].attachment = VK_ATTACHMENT_UNUSED;
         }
+
+        colorAttachmentReferenceCount += 1;
     }
 
     subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;