fix build failures

Author: RalfJung

benches/helpers/miri_helper.rs

@@ -31,6 +31,7 @@ impl rustc_driver::Callbacks for MiriCompilerCalls<'_> {
             self.bencher.iter(|| {
                 let config = miri::MiriConfig {
                     validate: true,
+                    stacked_borrows: true,
                     communicate: false,
                     ignore_leaks: false,
                     excluded_env_vars: vec![],

src/bin/miri-rustc-tests.rs

@@ -46,6 +46,7 @@ impl rustc_driver::Callbacks for MiriCompilerCalls {
                             {
                                 let config = MiriConfig {
                                     validate: true,
+                                    stacked_borrows: true,
                                     communicate: false,
                                     ignore_leaks: false,
                                     excluded_env_vars: vec![],
@@ -67,6 +68,7 @@ impl rustc_driver::Callbacks for MiriCompilerCalls {
             } else if let Some((entry_def_id, _)) = tcx.entry_fn(LOCAL_CRATE) {
                 let config = MiriConfig {
                     validate: true,
+                    stacked_borrows: true,
                     communicate: false,
                     ignore_leaks: false,
                     excluded_env_vars: vec![],