build regression checker as well

testsuite/src/bin/regression_checker.rs

@@ -1 +1,9 @@
-fn main() {}
+fn main() -> anyhow::Result<()> {
+    let root_var =
+        std::env::var("MINIMIZE_RUNTEST_ROOTS").expect("MINIMIZE_RUNTEST_ROOTS env var not found");
+    let roots = root_var.split(",").collect::<Vec<_>>();
+
+    let proj_dir = std::env::current_dir().expect("current dir not found");
+
+    testsuite::ensure_correct_minimization(&proj_dir, roots)
+}