It's not so trivial anymore.
It might be worthwhile to focus the problem a little more. I suggest trying to compile with a lesser arch
like core2 to see if you can, then try to other arches until you identify the one that fails.
The problem seems to be with the compile environment but it could also be your CPU. If it's an AMD it
adds another dimension because their implementation of some features is incompatible with Intel.
The RELEASE_NOTES have some tips.
Won't help, he needs to update binutils. Even if he uses -march=core2 it will still emit AVX2 instructions and old GNU assembler will break the compilation -- the file responsible is algo/argon2/ar2/sj/scrypt-jane-mix_salsa64-avx2.h, it will emit that instruction no matter what -march compiler option is provided.
You can easily replicate that problem yourself with installing gcc 4.8 and binutils 2.20 (which doesn't support avx2) in a chroot, container or virtual machine.
Interesting. It seems you're right but only because the compiler was upgraded, otherwise the AVX2 code would have been skipped:
#if (COMPILER_GCC >= 40700)
#define X86_64ASM_AVX2
I agree the way forward would be to upgrade all of gcc's dependencies: rpm -q --requires gcc