RFR: 8327994: Update code gen in CallGeneratorHelper [v2]

[Jorn Vernee]

> Update the code gen code in CallGeneratorHelper to reflect the latest state of the libTest(Downcall/Upcall)(Stack).c and shared.h files.
> 
> - The previous code wanted users to pipe stdout into a file. But, since we have 5 files that need to be created, and the names of those files is important too, I've changed the script to write to those files directly instead.
> - I moved the definition of `S_FFFF` to libVarArgs.c where it's used, as it's not actually generated by CallGeneratorHelper.
> - GitHub doesn't render the changes to some of the files, but those files only contain either white space changes (some missing spaces after `,`), and copyright header updates.

Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:

  Delete extra space
  
  Co-authored-by: Andrey Turbanov <turbanoff at gmail.com>

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/18269/files
  - new: https://git.openjdk.org/jdk/pull/18269/files/e66b7671..d282ecbd

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18269&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18269&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/18269.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18269/head:pull/18269

PR: https://git.openjdk.org/jdk/pull/18269