RFR: 8299261: Clean up AWT D3D exports

[Daniel Jeliński]

Please review this patch that removes unnecessary exports from awt.dll.

The exports were introduced in e4c9db984fe1a3a9d06fb60e333e92df3b165454, and as far as I could tell, they were never used; the exported functions are only used inside awt.dll.

Verified that:
- debug and release builds finish successfully
- mach5 client libs tests pass

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Commit messages:
 - Clean up AWT D3D exports

Changes: https://git.openjdk.org/jdk/pull/11765/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11765&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8299261
  Stats: 144 lines in 8 files changed: 5 ins; 106 del; 33 mod
  Patch: https://git.openjdk.org/jdk/pull/11765.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11765/head:pull/11765

PR: https://git.openjdk.org/jdk/pull/11765