fix -lto_library filtering for apple-clang + gfortran on sdk26

[Chrismarsh]

This fixes #5473 where the filtering of -lto_library needs to be applied for xcode >= 16

[martin-frbg]

Uh, sorry for mishandling the initial merge conflict here...

[Chrismarsh]

I think I made the pr off of tag 0.3.30 too 😬

All correct now?

[martin-frbg]

I had removed the if gfortran conditional in #5436 already, maybe that's what made github flag a merge conflict where there was none (and unfortunately I compared with a local checkout from before that September 2 commit by mistake).
I'll do a squash-and-merge and hope it will end up looking as originally intended...