[Bug lto/63215] LTO causes symbols for builtin functions to be omitted from object files

[hubicka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63215

--- Comment #2 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
As an ugly workaround, marking them __attribute__ ((externally_visible, used))
should work. They will however be added into every binary that is linked with
them no mater if they are used or not.