8325189: Enable this-escape javac warning in java.base

Reviewed-by: alanb, erikj, naoto, smarks, ihse, joehw, lancea, weijun

src/java.base/share/classes/sun/util/locale/provider/FallbackLocaleProviderAdapter.java

@@ -45,6 +45,7 @@ public class FallbackLocaleProviderAdapter extends JRELocaleProviderAdapter {
     /**
      * Fallback provider only provides the ROOT locale data.
      */
+    @SuppressWarnings("this-escape")
     private final LocaleResources rootLocaleResources =
         new LocaleResources(this, Locale.ROOT);