Build the bootstrap seed without the function layout

The native bootstrap compares the seed's LLVM, which the Node-hosted
compiler emits, with the LLVM the native compiler emits for itself. The
seed's build applied the committed function layout and the native
compiler has none, so the two listed the same functions in different
orders. The layout only orders functions, so the seed is built without it.

scripts/bootstrap-seed.mjs

@@ -51,6 +51,10 @@ async function main() {
         ...process.env,
         SCRIPTC_NATIVE_EMIT_IR: "1",
         SCRIPTC_NATIVE_OPTIMIZATION: sanitize ? "dev" : "release",
+        // The bootstrap compares the seed's LLVM with the native compiler's
+        // own emission, which has no function layout. The layout only orders
+        // the functions, so the seed is built without it.
+        SCRIPTC_NATIVE_LAYOUT: "",
       },
     },
   );