vk/vulkan.h: Reformat structs to match revision 130

vk/vulkan.h: Reformat structs to match revision 130

Structs in the old version were specified as

typedef struct VkSomeThing_
{
   type                                        field; // comment
} VkSomeThing;

However, in the generated headers, you have

typedef struct {
   type                                        field;
} VkSomeThing;

This commit also removes some unneeded whitespaces.