Vulkan structs from extensions typedef'ed incorrectly
When generating Vulkan headers with header only and loaders enabled, extensions that have been migrated to Vulkan Core have an incorrect struct typedef in the header.  
For example, the output is:
```cpp
typedef struct VkBindImageMemoryInfo {
    VkStructureType   sType;
    const  void *                       pNext;
    VkImage                            image;
    VkDeviceMemory                     memory;
    VkDeviceSize                       memoryOffset;
} VkBindImageMemoryInfo;
typedef struct VkBindImageMemoryInfoKHR  VkBindImageMemoryInfoKHR;
```
Expected output should be:
```cpp
typedef struct VkBindImageMemoryInfo {
    VkStructureType   sType;
    const  void *                       pNext;
    VkImage                            image;
    VkDeviceMemory                     memory;
    VkDeviceSize                       memoryOffset;
} VkBindImageMemoryInfo;
typedef struct VkBindImageMemoryInfo  VkBindImageMemoryInfoKHR;
```
This example above can be reproduced with the VK_KHR_bind_memory2 extension, which is required for VMA.