Replace cfg(loom) with one that includes the feature flag

Author: notgull

src/lib.rs

@@ -32,10 +32,10 @@
 #![forbid(unsafe_code)]
 #![warn(missing_docs, missing_debug_implementations, rust_2018_idioms)]
 
-#[cfg(not(loom))]
+#[cfg(not(all(loom, feature = "loom")))]
 use std::sync;
 
-#[cfg(loom)]
+#[cfg(all(loom, feature = "loom"))]
 use loom::sync;
 
 use std::cell::Cell;