RFR: 8216400: improve handling of IOExceptions in JavaCompiler.close()

[Guoxiong Li]

Hi all,

This little patch enhances the code according to the comment by using a simplest way. I found [JDK-8069116](https://bugs.openjdk.java.net/browse/JDK-8069116) is a similar issue. A better way would be appreciated.

Thank you for taking the time to reivew.

Best Regards.

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Commit messages:
 - 8216400: improve handling of IOExceptions in JavaCompiler.close()

Changes: https://git.openjdk.java.net/jdk/pull/1895/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1895&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8216400
  Stats: 5 lines in 1 file changed: 0 ins; 4 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1895.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1895/head:pull/1895

PR: https://git.openjdk.java.net/jdk/pull/1895