Rollup merge of #61762 - Keruspe:rustbuild-libtest-fix, r=Mark-Simulacrum

rustbuild: fix libtest_stamp

Looks like an obvious copy/paste typo

src/bootstrap/builder.rs

@@ -787,7 +787,7 @@ impl<'a> Builder<'a> {
 
         let libtest_stamp = match cmd {
             "check" | "clippy" | "fix" => check::libtest_stamp(self, cmp, target),
-            _ => compile::libstd_stamp(self, cmp, target),
+            _ => compile::libtest_stamp(self, cmp, target),
         };
 
         let librustc_stamp = match cmd {