pub type PFN_vkReallocationFunction = Option<unsafe extern "system" fn(p_user_data: *mut c_void, p_original: *mut c_void, size: usize, alignment: usize, allocation_scope: SystemAllocationScope) -> *mut c_void>;
https://www.khronos.org/registry/vulkan/specs/1.3-extensions/man/html/PFN_vkReallocationFunction.html