Unbreak OSS windows CI

Summary:
Unused feature ig. Our internal and external lint configs being out of sync is incredibly annoying.

___

Differential Revision: D108569176

fbshipit-source-id: f54dab5bfe817bd606629fa9e7f89a7a2a07f8b9

Author: JakobDegen

app/buck2_util/src/lib.rs

@@ -9,7 +9,7 @@
  */
 
 #![feature(decl_macro)]
-#![feature(linkage)]
+#![cfg_attr(not(windows), feature(linkage))]
 #![feature(once_cell_try)]
 #![feature(used_with_arg)]