RFR: 8286481: Exception printed to stdout on Windows when storing transparent image in clipboard

[Alisen Chung]

Removed stacktrace from WClipboard

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

Commit messages:
 - removed printing stack trace

Changes: https://git.openjdk.java.net/jdk/pull/8871/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8871&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8286481
  Stats: 7 lines in 1 file changed: 0 ins; 6 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8871.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8871/head:pull/8871

PR: https://git.openjdk.java.net/jdk/pull/8871