8304139: Add <init> and <clinit> method constants to ConstantDescs

Reviewed-by: mchung

src/java.base/share/classes/java/lang/invoke/MethodHandleInfo.java

@@ -160,7 +160,8 @@ public interface MethodHandleInfo {
 
     /**
      * Returns the name of the cracked method handle's underlying member.
-     * This is {@code "<init>"} if the underlying member was a constructor,
+     * This is {@value java.lang.constant.ConstantDescs#INIT_NAME}
+     * if the underlying member was a constructor,
      * else it is a simple method name or field name.
      * @return the simple name of the underlying member
      */