Add the no-builtins attribute to functions when no_builtins is applied at the crate level.

When `no_builtins` is applied at the crate level, we should add the
`no-builtins` attribute to each function to ensure it takes effect in LTO.

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -335,6 +335,10 @@ pub fn from_fn_attrs<'ll, 'tcx>(
     to_add.extend(probestack_attr(cx));
     to_add.extend(stackprotector_attr(cx));
 
+    if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NO_BUILTINS) {
+        to_add.push(llvm::CreateAttrString(cx.llcx, "no-builtins"));
+    }
+
     if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::COLD) {
         to_add.push(AttributeKind::Cold.create_attr(cx.llcx));
     }