FYI: 8243131: DisableMaskCache in MTLMaskFill to maintain proper state

[Jayathirth D V]

We have local cache state management(unlike opengl which uses check_previous_op) and its better if we disable mask
cache and not just flush it in MaskFill.

-------------

Commit messages:
 - 8243131: DisableMaskCache in MTLMaskFill to maintain proper state

Changes: https://git.openjdk.java.net/lanai/pull/28/files
 Webrev: https://webrevs.openjdk.java.net/lanai/28/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8243131
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/lanai/pull/28.diff
  Fetch: git fetch https://git.openjdk.java.net/lanai pull/28/head:pull/28

PR: https://git.openjdk.java.net/lanai/pull/28