RFR: 8247464: Memory Leak in MTLBlitLoops_CopyArea() method

[Ajit Ghaisas]

Issue : https://bugs.openjdk.java.net/browse/JDK-8247464
Fix : Mark newly allocated buffer as 'autorelease'

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Commit messages:
 - mark buff autorelease

Changes: https://git.openjdk.java.net/lanai/pull/57/files
 Webrev: https://webrevs.openjdk.java.net/lanai/57/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8247464
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/lanai/pull/57.diff
  Fetch: git fetch https://git.openjdk.java.net/lanai pull/57/head:pull/57

PR: https://git.openjdk.java.net/lanai/pull/57