RFR: JDK-8283140: Remove unused encoding classes/operands from x86_64.ad [v5]

[Cesar Soares Lucas]

> These encoding classes became dead code when the instructions' definitions were patched to use the MacroAssembler.
> 
> Tested with tier 1-3 on Linux, Windows & MacOS.

Cesar Soares Lucas has updated the pull request incrementally with one additional commit since the last revision:

  Fix typo / Fix inst mark location.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/16319/files
  - new: https://git.openjdk.org/jdk/pull/16319/files/e32a421a..d34e4709

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16319&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16319&range=03-04

  Stats: 5 lines in 1 file changed: 0 ins; 2 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/16319.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16319/head:pull/16319

PR: https://git.openjdk.org/jdk/pull/16319