Add a dependency on the alloc crate

Xargo.toml

@@ -0,0 +1,2 @@
+[target.x86_64-blog_os.dependencies]
+alloc = {}

src/lib.rs

@@ -1,9 +1,14 @@
 #![feature(lang_items)]
 #![feature(const_fn)]
+#![feature(alloc)]
 #![feature(const_unique_new)]
 #![feature(unique)]
 #![no_std]
 
+
+#[macro_use]
+extern crate alloc;
+
 extern crate rlibc;
 extern crate volatile;
 extern crate spin;