make tests more robust

Author: RalfJung

src/test/codegen/unwind-extern-imports.rs

@@ -4,10 +4,10 @@
 #![feature(unwind_attributes)]
 
 extern {
-// CHECK: Function Attrs: nounwind
+// CHECK: Function Attrs:{{.*}}nounwind
 // CHECK-NEXT: declare void @extern_fn
     fn extern_fn();
-// CHECK-NOT: Function Attrs: nounwind
+// CHECK-NOT: Function Attrs:{{.*}}nounwind
 // CHECK: declare void @unwinding_extern_fn
     #[unwind(allowed)]
     fn unwinding_extern_fn();