RFR: JDK-8289741 : Remove unused imports from DTDBuilder.java

[ScientificWare]

This is tracked in JBS as

[JDK-8289741](https://bugs.openjdk.org/browse/JDK-8289741)

> **Remove unused imports from DTDBuilder.java**
Some imports are no more used.

- java.io.FileNotFoundException;
- java.io.BufferedInputStream;
- java.io.OutputStream;
- java.util.BitSet;
- java.util.StringTokenizer;
- java.util.Properties;
- java.util.zip.DeflaterOutputStream;
- java.util.zip.Deflater;
- java.net.URL;

-------------

Commit messages:
 - Merge branch 'openjdk:master' into scientificware-patch-001-DTDBuilder
 - Merge branch 'openjdk:master' into scientificware-patch-001-DTDBuilder
 - Merge branch 'openjdk:master' into scientificware-patch-001-DTDBuilder
 - Merge branch 'openjdk:master' into scientificware-patch-001-DTDBuilder
 - Merge branch 'openjdk:master' into scientificware-patch-001-DTDBuilder
 - Merge branch 'openjdk:master' into scientificware-patch-001-DTDBuilder
 - Remove unused imports.

Changes: https://git.openjdk.org/jdk/pull/9360/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9360&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8289741
  Stats: 11 lines in 1 file changed: 0 ins; 10 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/9360.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9360/head:pull/9360

PR: https://git.openjdk.org/jdk/pull/9360