RFR: 8371087: Remove unused dependency on jdk.unsupported from javafx.graphics [v2]

[Kevin Rushforth]

> This PR removes the unused dependency on `jdk.unsupported` from `javafx.graphics` as a followup to [JDK-8334137](https://bugs.openjdk.org/browse/JDK-8334137), which replaced the use of `sun.misc.Unsafe` with FFM in PR #1814. `sun.misc.Unsafe` was the only use of `jdk.unsupported`, so it can now be removed.

Kevin Rushforth has updated the pull request incrementally with one additional commit since the last revision:

  Remove unneeded '-XDignore.symbol.file' option

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1957/files
  - new: https://git.openjdk.org/jfx/pull/1957/files/e390af9a..fe26e6fc

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1957&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1957&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jfx/pull/1957.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1957/head:pull/1957

PR: https://git.openjdk.org/jfx/pull/1957