fix: use compile-time flag

Author: QEDK

src/lib.rs

@@ -174,9 +174,12 @@ impl<T> Producer<T> {
         unsafe {
             let next_index = next_head & self.queue.0.mask.0;
             let next_slot = self.queue.0.buffer.0.add(next_index);
-            if is_x86_feature_detected!("sse") {
+            #[cfg(target_feature = "sse")]
+            {
                 prefetch_read(next_slot as *const u8);
-            } else {
+            }
+            #[cfg(target_feature = "prfchw")]
+            {
                 prefetch_write(next_slot as *const u8);
             }
         }