GNU: Do not use "fat-lto-objects" flags for IPO on Apple platforms
Fat LTO objects contain both traditional object code and the LTO bitcode
IR, but the GNU compiler does not support them on Apple platforms.
A compile error is raised when -f[no-]fat-lto-objects
flags are used,
so avoid them.
This also implies that static Fortran libraries cannot be built with IPO.
Fixes: #25931 (closed)
Topic-rename: lto-gnu-apple
Edited by Brad King