The way we need to do PGO builds for foot changed. The gcc build was
unaffected by this, but has been updated to the new instructions. For
clang using the outdated introduction meant that the PGO build was
broken when using clang for building foot with PGO enabled.
This has been fixed by updating to the new build instructions for both
gcc and clang when using PGO:
https://codeberg.org/dnkl/foot/pulls/420
foot.override { stdenv = llvmPackages_11.stdenv; } now works as expected.
68a1f6f391