Update winapi to 0.3.4

Cargo.toml

@@ -8,7 +8,7 @@ repository = "https://github.com/servo/heapsize"
 build = "build.rs"
 
 [target.'cfg(windows)'.dependencies]
-kernel32-sys = "0.2.1"
+winapi = { version = "0.3.4", features = ["std", "heapapi"] }
 
 [features]
 unstable = []

src/lib.rs

@@ -1,10 +1,10 @@
 //! Data structure measurement.
 
 #[cfg(target_os = "windows")]
-extern crate kernel32;
+extern crate winapi;
 
 #[cfg(target_os = "windows")]
-use kernel32::{GetProcessHeap, HeapSize, HeapValidate};
+use winapi::um::heapapi::{GetProcessHeap, HeapSize, HeapValidate};
 use std::borrow::Cow;
 use std::cell::{Cell, RefCell};
 use std::collections::{BTreeMap, HashSet, HashMap, LinkedList, VecDeque};