Fix npe if <include> does not have a "name" attribute

PR: 25982
Obtained from: Dawid Weiss


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@275875 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/types/PatternSet.java

@@ -123,7 +123,7 @@ public class PatternSet extends DataType implements Cloneable {
         }
 
         public String toString() {
-            StringBuffer buf = new StringBuffer(name);
+            StringBuffer buf = new StringBuffer(name != null ? name : "");
             if ((ifCond != null) || (unlessCond != null)) {
                 buf.append(":");
                 String connector = "";