RFR: 8324765: C2 SuperWord: remove dead code: SuperWord::insert_extracts [v2]

[Emanuel Peter]

> Subtask of https://github.com/openjdk/jdk/pull/16620
> 
> As far as all tests and code study have showed me, SuperWord::insert_extracts is dead.
> 
> I am replacing it with verification code, that checks that no ExtractNode is required.
> 
> **Details**
> 
> All the relevant cases are marked as "unprofitable" in `SuperWord::profitable`, see:
> https://github.com/openjdk/jdk/blob/dfdd2174d7af5e3e995147484db17b45b006f6d0/src/hotspot/share/opto/superword.cpp#L1912-L1915

Emanuel Peter has updated the pull request incrementally with one additional commit since the last revision:

  typo fix by Christian
  
  Co-authored-by: Christian Hagedorn <christian.hagedorn at oracle.com>

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/17589/files
  - new: https://git.openjdk.org/jdk/pull/17589/files/8a08a4f2..c9fe0153

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17589&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17589&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/17589.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17589/head:pull/17589

PR: https://git.openjdk.org/jdk/pull/17589