Typical errors look like:
>proto_http.c:(.text+0xbfc): undefined reference to `__atomic_fetch_add_8'
gyakovlev has investigated this here: https://bugs.gentoo.org/719662#c3.
The gist is that libatomic is not always part of libstdc++. It looks like this is the case on non-x86 32 bit arches, but arm in at least some of these bugs has already been identified by upstream and handled in their build system.
Patches should be trivial in just adding -latomic on ppc/other 32-bit arches. With --as-needed in LDFLAGS, it shouldn't matter if we add it when it's unnecessary, I think.
We may need to come up with a neat macro/conditional to cleanly match only e.g. ppc and not ppc64.
I have assigned this to base-system@ for now because it seems to be an autoconf bug exposed by newer versions of GCC (>= 8).
Please reassign if you feel this is not appropriate.
ppc32 check should generally be
> defined(__powerpc__) && !defined(__powerpc64__)
because __powerpc__ also defined on ppc64 hosts.