[Bug algol68/123733] Bootstrap fails: implicit declaration of GC_is_init_called

[jemarch at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123733

--- Comment #8 from Jose E. Marchesi <jemarch at gcc dot gnu.org> ---
The commit r16-7016-g9c8bb50ab9896924a95af78c345c301c36224fb6 should
result in libgc to not be used at all in systems where the system is
not recent enough to provide GC_is_init_called.