Mark unpark() as #[inline].

library/std/src/thread/mod.rs

@@ -1086,6 +1086,7 @@ impl Thread {
     /// parked_thread.join().unwrap();
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
     pub fn unpark(&self) {
         self.inner.parker.unpark();
     }

library/std/src/thread/parker/linux.rs

@@ -57,6 +57,7 @@ impl Parker {
         }
     }
 
+    #[inline]
     pub fn unpark(&self) {
         // Change PARKED=>NOTIFIED, EMPTY=>NOTIFIED, or NOTIFIED=>NOTIFIED, and
         // wake the thread in the first case.