FOP-2505: SVG -> PDF throws java.lang.OutOfMemoryError: Java heap space

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@1723072 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/fop/pdf/PDFPattern.java

@@ -321,7 +321,7 @@ public class PDFPattern extends PDFPathPaint {
         if (pdfStream != null) {
             length += pdfStream.outputStreamData(encodedStream, stream);
         }
-
+        patternDataStream = null;
         return length;
     }