Add a test for thread locals.

tests/run-pass/concurrency/thread_locals.rs

@@ -0,0 +1,48 @@
+#![feature(thread_local)]
+
+use std::thread;
+
+#[thread_local]
+static mut A: u8 = 0;
+#[thread_local]
+static mut B: u8 = 0;
+static mut C: u8 = 0;
+
+unsafe fn get_a_ref() -> *mut u8 {
+    &mut A
+}
+
+fn main() {
+
+    unsafe {
+        let x = get_a_ref();
+        *x = 5;
+        assert_eq!(A, 5);
+        B = 15;
+        C = 25;
+    }
+    
+    thread::spawn(|| {
+        unsafe {
+            assert_eq!(A, 0);
+            assert_eq!(B, 0);
+            assert_eq!(C, 25);
+            B = 14;
+            C = 24;
+            let y = get_a_ref();
+            assert_eq!(*y, 0);
+            *y = 4;
+            assert_eq!(A, 4);
+            assert_eq!(*get_a_ref(), 4);
+            
+        }
+    }).join().unwrap();
+
+    unsafe {
+        assert_eq!(*get_a_ref(), 5);
+        assert_eq!(A, 5);
+        assert_eq!(B, 15);
+        assert_eq!(C, 24);
+    }
+    
+}