<AWT Dev> RFR: 8263142: Delete unused entry points in libawt/libawt_xawt/libawt_headless

[Sergey Bylokhov]

During the review of:
   8254024: Enhance native libs for AWT and Swing to work with GraalVM Native Image

I have found that some of the entry points in our libraries are never used, and can be removed, we do not need to update the code to make it work in static_build.

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Commit messages:
 - Initial fix

Changes: https://git.openjdk.java.net/jdk/pull/2865/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2865&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263142
  Stats: 220 lines in 3 files changed: 0 ins; 217 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2865.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2865/head:pull/2865

PR: https://git.openjdk.java.net/jdk/pull/2865