[Bug lto/97524] Compiling with -flto=auto fails in make is not installed

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97524

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #2)
> Well, can't it fall back to serial compilation?

It could, maybe with some diagnostic.  It could also use fork-based
parallelism.