Warning: "variable ‘right’ set but not used" in `optimizer_cases.c.h`

[sobolevn]

Bug report

CC @Fidget-Spinner

Linked PRs

• gh-116420: Fix unused var compilation warnings #116466

[Fidget-Spinner]

Will fix this soon with another PR later. Don't want to run like 4 macOS jobs just for a (void)right :).

[Fidget-Spinner]

Nevermind, it's big enough that I created its own PR for it.