Rollup merge of #42098 - japaric:gh42097, r=Mark-Simulacrum

Mark-Simulacrum · web-flow · commit 950e4266e61d · 2017-05-20T17:48:15.000-06:00
core: fix unused_macro warning when compiling the crate for a target with max-atomic-width = 0 fixes #42097
diff --git a/src/libcore/sync/atomic.rs b/src/libcore/sync/atomic.rs
@@ -918,6 +918,7 @@ impl<T> AtomicPtr<T> {
     }
 }
 
+#[cfg(target_has_atomic = "ptr")]
 macro_rules! atomic_int {
     ($stable:meta,
      $stable_cxchg:meta,
