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