move enzyme flags from general cargo to rustc-specific cargo

Signed-off-by: onur-ozkan <work@onurozkan.dev>

Author: onur-ozkan

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

@@ -1057,6 +1057,10 @@ pub fn rustc_cargo(
     // killed, rather than having an error bubble up and cause a panic.
     cargo.rustflag("-Zon-broken-pipe=kill");
 
+    if builder.config.llvm_enzyme {
+        cargo.rustflag("-l").rustflag("Enzyme-19");
+    }
+
     // We currently don't support cross-crate LTO in stage0. This also isn't hugely necessary
     // and may just be a time sink.
     if compiler.stage != 0 {

src/bootstrap/src/core/builder.rs

@@ -1591,12 +1591,6 @@ impl<'a> Builder<'a> {
             rustflags.arg(sysroot_str);
         }
 
-        // https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/.E2.9C.94.20link.20new.20library.20into.20stage1.2Frustc
-        if self.config.llvm_enzyme {
-            rustflags.arg("-l");
-            rustflags.arg("Enzyme-19");
-        }
-
         let use_new_symbol_mangling = match self.config.rust_new_symbol_mangling {
             Some(setting) => {
                 // If an explicit setting is given, use that