RFR: 8253657: Lanai: Refactor MTLTexturePool - getTexture

[Alexey Ushakov]

Returned autorelease object. Corrected memory management of MTLTexturePoolItem objects

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Commit messages:
 - 8253657: Lanai: Refactor MTLTexturePool - getTexture should return autorelease object

Changes: https://git.openjdk.java.net/lanai/pull/109/files
 Webrev: https://webrevs.openjdk.java.net/?repo=lanai&pr=109&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8253657
  Stats: 11 lines in 5 files changed: 4 ins; 5 del; 2 mod
  Patch: https://git.openjdk.java.net/lanai/pull/109.diff
  Fetch: git fetch https://git.openjdk.java.net/lanai pull/109/head:pull/109

PR: https://git.openjdk.java.net/lanai/pull/109