Fix typo from rust-lang#65214

Amanieu · Amanieu · commit 3de7698e124f · 2019-10-21T13:30:43.000+01:00
diff --git a/src/libstd/panic.rs b/src/libstd/panic.rs
@@ -264,7 +264,7 @@ impl RefUnwindSafe for atomic::AtomicI128 {}
 #[cfg(target_has_atomic_load_store = "ptr")]
 #[stable(feature = "unwind_safe_atomic_refs", since = "1.14.0")]
 impl RefUnwindSafe for atomic::AtomicUsize {}
-#[cfg(target_hastarget_has_atomic_load_store_atomic = "8")]
+#[cfg(target_has_atomic_load_store = "8")]
 #[unstable(feature = "integer_atomics", issue = "32976")]
 impl RefUnwindSafe for atomic::AtomicU8 {}
 #[cfg(target_has_atomic_load_store = "16")]
