RFR: JDK-8273387: remove some unreferenced gtk-related functions [v2]

[Matthias Baesken]

> Please review this small change.
> Looks like there are a few functions, like gtk2_paint_diamond, that are unreferenced and can be removed.
> 
> Thanks, Matthias

Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:

  remove fp_gtk_paint_diamond function pointer init

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5384/files
  - new: https://git.openjdk.java.net/jdk/pull/5384/files/3434b114..627cffa0

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5384&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5384&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5384.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5384/head:pull/5384

PR: https://git.openjdk.java.net/jdk/pull/5384