Fix O(tests) stack usage in edition 2024 mergeable doctests

Author: saethlin

src/librustdoc/doctest/runner.rs

@@ -136,7 +136,7 @@ mod __doctest_mod {{
 
 #[rustc_main]
 fn main() -> std::process::ExitCode {{
-const TESTS: [test::TestDescAndFn; {nb_tests}] = [{ids}];
+const TESTS: &[test::TestDescAndFn] = &[{ids}];
 let test_marker = std::ffi::OsStr::new(__doctest_mod::RUN_OPTION);
 let test_args = &[{test_args}];
 const ENV_BIN: &'static str = \"RUSTDOC_DOCTEST_BIN_PATH\";
@@ -160,7 +160,6 @@ eprintln!(\"WARNING: No rustdoc doctest environment variable provided so doctest
 the same process\");
 std::process::Termination::report(test::test_main(test_args, Vec::from(TESTS), None))
 }}",
-            nb_tests = self.nb_tests,
             output = self.output,
             ids = self.ids,
         )