fix the ponctuation of the error message

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@1367299 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/taskdefs/Definer.java

@@ -226,7 +226,7 @@ public abstract class Definer extends DefBase {
             } else {
                 throw new BuildException(
                         "Only antlib URIs can be located from the URI alone,"
-                                + "not the URI " + getURI());
+                                + " not the URI '" + getURI() + "'");
             }
         }