[Bug bootstrap/64320] Missing config.h during findcomp.cc compilation

[townsend at astro dot wisc.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64320

--- Comment #1 from Rich Townsend <townsend at astro dot wisc.edu> ---
OK, it seems that this bug comes from building with srcdir == objdir. If I
build in a separate directory, then the problem goes away.

As an aside, I hadn't realized that using srcdir == objdir is generally
discouraged (see, e.g., https://gcc.gnu.org/install/configure.html). Is this a
recent change, or have I always been doing it wrong?