RFR: 8262115: Crash on graphics card switch when Metal API validation enabled

[Ajit Ghaisas]

First 3 errors observed during testing of JDK-8261714 are being fixed in this PR.

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Commit messages:
 - GPU switch partial fix

Changes: https://git.openjdk.java.net/lanai/pull/200/files
 Webrev: https://webrevs.openjdk.java.net/?repo=lanai&pr=200&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262115
  Stats: 40 lines in 6 files changed: 34 ins; 1 del; 5 mod
  Patch: https://git.openjdk.java.net/lanai/pull/200.diff
  Fetch: git fetch https://git.openjdk.java.net/lanai pull/200/head:pull/200

PR: https://git.openjdk.java.net/lanai/pull/200