Failing to build from git master on Arch Linux

Hi, after noticing recent commit activity I held back reporting broken build failures on Arch Linux for a while, assuming things would sort themselves out. Today I tried another build from latest git at commit d07cb5b. Here are my observations:

...
./goldilocks_gen_tables > GEN/goldilocks_tables.c || (rm GEN/goldilocks_tables.c; exit 1)
/bin/sh: line 1: 104188 Illegal instruction     (core dumped) ./goldilocks_gen_tables > GEN/goldilocks_tables.c
make[2]: *** [Makefile:1333: GEN/goldilocks_tables.c] Error 1
make[2]: Leaving directory '/home/glitsj16/libgoldilocks/src'
make[1]: *** [Makefile:420: all-recursive] Error 1
make[1]: Leaving directory '/home/glitsj16/libgoldilocks'
make: *** [Makefile:351: all] Error 2

OS: Arch Linux

$ pacman -Q gcc make
gcc 9.3.0-1
make 4.3-1

Full build log: https://gist.github.com/glitsj16/67836b5e1c7aac97deeff161500d40c3

[mytbk]

I've just built one with PKGBUILD, and found:
variables.am:ARCHFLAGS = -maes -mavx2 -mbmi2 #TODO

So it'll be built with AVX2 on, but my machine is a Sandy Bridge, so get a SIGILL.