[jdk11u-dev] RFR: 8280002: jmap -histo may leak stream

[Thomas Stuefe]

Clean backport of a small patch that fixes a leak (file handle + memory) introduced with JDK-8215624.

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Commit messages:
 - Backport c359c358c8ebaf7b1dddbc4b499a7aae65ba6736

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/768/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=768&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8280002
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/768.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/768/head:pull/768

PR: https://git.openjdk.java.net/jdk11u-dev/pull/768