RFR: 8334495: Use FFM instead of jdk.internal.misc.Unsafe in java.desktop font implementation [v4]

[Phil Race]

> Migrate font code from jdk.internal.misc.Unsafe to using FFM.
> This reduces the coupling between the java.desktop module and the internals of the java.base module.
> 
> The code being changed here is not particularly performance sensitive, and it is not executed in the most common cases.
> The main impact performance-wise is a total of around 37ms in initialisation costs on my x64 macbook.
> A minimal program that just draws a string to an image - does not even put up a window - runs at around 690-700ms.
> There's variability in that number and the overall time for a JDK without the change is around (660-670ms)
> In the small test, this is the first and only use of FFM, so the one-off part cost should move elsewhere when FFM starts
> to be used earlier in the JDK itself.

Phil Race has updated the pull request incrementally with one additional commit since the last revision:

  8334495

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Changes:
  - all: https://git.openjdk.org/jdk/pull/19777/files
  - new: https://git.openjdk.org/jdk/pull/19777/files/d3ca7f4b..b0053f88

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19777&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19777&range=02-03

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/19777.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19777/head:pull/19777

PR: https://git.openjdk.org/jdk/pull/19777