Remove unnecessary clone call for panic_strategy

Author: whitfin

src/librustc_metadata/cstore.rs

@@ -207,6 +207,6 @@ impl CrateMetadata {
     }
 
     pub fn panic_strategy(&self) -> PanicStrategy {
-        self.root.panic_strategy.clone()
+        self.root.panic_strategy
     }
 }