More fixes for undeclared identifiers with old Vulkan SDK

Fixes #413 - thanks @HermanWolf
diff --git a/include/vk_mem_alloc.h b/include/vk_mem_alloc.h
index 92700cf..ccb9a8f 100644
--- a/include/vk_mem_alloc.h
+++ b/include/vk_mem_alloc.h
@@ -15158,7 +15158,7 @@
     if(funcs->vkGetDeviceBufferMemoryRequirements)
     {
         // Can query straight from VkBufferCreateInfo :)
-        VkDeviceBufferMemoryRequirements devBufMemReq = {VK_STRUCTURE_TYPE_DEVICE_BUFFER_MEMORY_REQUIREMENTS};
+        VkDeviceBufferMemoryRequirementsKHR devBufMemReq = {VK_STRUCTURE_TYPE_DEVICE_BUFFER_MEMORY_REQUIREMENTS_KHR};
         devBufMemReq.pCreateInfo = pBufferCreateInfo;
 
         VkMemoryRequirements2 memReq = {VK_STRUCTURE_TYPE_MEMORY_REQUIREMENTS_2};
@@ -15210,7 +15210,7 @@
     if(funcs->vkGetDeviceImageMemoryRequirements)
     {
         // Can query straight from VkImageCreateInfo :)
-        VkDeviceImageMemoryRequirements devImgMemReq = {VK_STRUCTURE_TYPE_DEVICE_IMAGE_MEMORY_REQUIREMENTS_KHR};
+        VkDeviceImageMemoryRequirementsKHR devImgMemReq = {VK_STRUCTURE_TYPE_DEVICE_IMAGE_MEMORY_REQUIREMENTS_KHR};
         devImgMemReq.pCreateInfo = pImageCreateInfo;
         VMA_ASSERT(pImageCreateInfo->tiling != VK_IMAGE_TILING_DRM_FORMAT_MODIFIER_EXT_COPY && (pImageCreateInfo->flags & VK_IMAGE_CREATE_DISJOINT_BIT_COPY) == 0 &&
             "Cannot use this VkImageCreateInfo with vmaFindMemoryTypeIndexForImageInfo as I don't know what to pass as VkDeviceImageMemoryRequirements::planeAspect.");