PDFBOX-5660: avoid default encoding

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1927157 13f79535-47bb-0310-9956-ffa450edef68

Author: THausherr

pdfbox/src/main/java/org/apache/pdfbox/pdmodel/font/TrueTypeEmbedder.java

@@ -22,6 +22,7 @@
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
@@ -87,7 +88,7 @@ abstract class TrueTypeEmbedder implements Subsetter
             InputStream is = ttf.getOriginalData();
             byte[] b = new byte[4];
             is.mark(b.length);
-            if (is.read(b) == b.length && new String(b).equals("ttcf"))
+            if (is.read(b) == b.length && new String(b, StandardCharsets.US_ASCII).equals("ttcf"))
             {
                 is.close();
                 throw new IOException("Full embedding of TrueType font collections not supported");