Build fixes for GCC and the Vulkan-Hpp in ::gentoo:
- set preferredLargeHeapBlockSize once, in declaration order: GCC rejects a
  field designated twice (clang only warns)
- name the type when resetting hdr_format: "= {}" is ambiguous between
  vk::SurfaceFormatKHR's two operator= overloads

--- a/engine/gpu/shadps4/video_core/renderer_vulkan/vk_instance.cpp
+++ b/engine/gpu/shadps4/video_core/renderer_vulkan/vk_instance.cpp
@@ -991,7 +991,6 @@
     }();
     const VmaAllocatorCreateInfo allocator_info = {
         .flags = VMA_ALLOCATOR_CREATE_BUFFER_DEVICE_ADDRESS_BIT,
-        .preferredLargeHeapBlockSize = block_size,
         .physicalDevice = physical_device,
         .device = *device,
         .preferredLargeHeapBlockSize = block_size,
--- a/engine/gpu/shadps4/video_core/renderer_vulkan/vk_swapchain.cpp
+++ b/engine/gpu/shadps4/video_core/renderer_vulkan/vk_swapchain.cpp
@@ -388,7 +388,7 @@
     if ((features & composite_features) != composite_features) {
         std::printf("HDR output: %s cannot hold the SDR picture for the encode; staying SDR\n",
                     vk::to_string(surface_format.format).c_str());
-        hdr_format = {};
+        hdr_format = vk::SurfaceFormatKHR{};
         return;
     }
     const float display_peak = settings.hdr_display_peak.load();