win32: Fix vk_mem_alloc.h compatibility break.

Set WINVER to less than Vista to maintain compatibility with Windows XP.

vulkan/vk_mem_alloc_implementation.cpp

@@ -1,2 +1,2 @@
 #define VMA_IMPLEMENTATION
-#include "vk_mem_alloc.hpp"
+#include "vulkan_context.hpp"

vulkan/vulkan_context.cpp

@@ -2,7 +2,6 @@
 #include <cstring>
 #include <tuple>
 #include "vulkan_context.hpp"
-#include "vk_mem_alloc.hpp"
 #include "slang_shader.hpp"
 #include "vulkan/vulkan.hpp"
 

vulkan/vulkan_context.hpp

@@ -3,6 +3,10 @@
 #ifdef VK_USE_PLATFORM_XLIB_KHR
 #include <X11/Xlib.h>
 #endif
+#ifdef VK_USE_PLATFORM_WIN32_KHR
+#undef WINVER
+#define WINVER 0x599
+#endif
 #include "vk_mem_alloc.hpp"
 #include "vulkan/vulkan.hpp"
 #include "vulkan_swapchain.hpp"
@@ -46,9 +50,6 @@ class Context
     bool init_device(int preferred_device = 0);
     bool init_command_pool();
     bool init_descriptor_pool();
-    void create_vertex_buffer();
-
-    vk::UniquePipeline create_generic_pipeline();
 
 #ifdef VK_USE_PLATFORM_XLIB_KHR
     Display *xlib_display;

vulkan/vulkan_texture.hpp

@@ -1,6 +1,5 @@
 #pragma once
 
-#include "vk_mem_alloc.hpp"
 #include "vulkan_context.hpp"
 
 namespace Vulkan