RFR: 8255565: [Vector API] Add missing format strings for extract instructs in x86.ad

[Jie Fu]

Hi all,

Extract instructs in x86.ad like extractI/vextractI/extractL missed the format strings (format %{ ... %}).
When analyzing or debugging with PrintOptoAssembly, it's hard to map the generated assembly code to the MachNode instructs without the format strings.
So it would be better to fix it.

Thanks a lot.
Best regards,
Jie

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Commit messages:
 - 8255565: [Vector API] Add missing format strings for extract instructs in x86.ad

Changes: https://git.openjdk.java.net/jdk/pull/920/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=920&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255565
  Stats: 8 lines in 1 file changed: 8 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/920.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/920/head:pull/920

PR: https://git.openjdk.java.net/jdk/pull/920