update outdated comment

Author: ZuseZ4

src/bootstrap/src/core/build_steps/compile.rs

@@ -1049,9 +1049,9 @@ pub fn rustc_cargo(
     // <https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Internal.20lint.20for.20raw.20.60print!.60.20and.20.60println!.60.3F>.
     cargo.rustflag("-Zon-broken-pipe=kill");
 
-    // We temporarily disable linking here as part of some refactoring.
-    // This way, people can manually use -Z llvm-plugins and -C passes=enzyme for now.
-    // In a follow-up PR, we will re-enable linking here and load the pass for them.
+    // We want to link against registerEnzyme and in the future we want to use additional
+    // functionality from Enzyme core. For that we need to link against Enzyme.
+    // FIXME(ZuseZ4): Get the LLVM version number automatically instead of hardcoding it.
     if builder.config.llvm_enzyme {
         cargo.rustflag("-l").rustflag("Enzyme-19");
     }