Add lintcheck to packages linted by dogfood test

Author: smoelius

tests/dogfood.rs

@@ -20,7 +20,14 @@ fn dogfood_clippy() {
     }
 
     // "" is the root package
-    for package in &["", "clippy_dev", "clippy_lints", "clippy_utils", "rustc_tools_util"] {
+    for package in &[
+        "",
+        "clippy_dev",
+        "clippy_lints",
+        "clippy_utils",
+        "lintcheck",
+        "rustc_tools_util",
+    ] {
         run_clippy_for_package(package, &["-D", "clippy::all", "-D", "clippy::pedantic"]);
     }
 }