Trying to build m2crypto 0.35.2 yields a weird error:

running build_ext
building 'M2Crypto._m2crypto' extension
swigging SWIG/_m2crypto.i to SWIG/_m2crypto_wrap.c
swig -python -py3 -D_riscv64_ -I/usr/include/python3.7m -I/usr/include -I/usr/include/openssl -I/usr/lib/gcc/riscv64-unknown-linux-gnu/9.3.0/include -I/usr/local/include -I/usr/lib/gcc/riscv64-unknown-linux-gnu/9.3.0/include-fixed -I/usr/include -includeall -modern -builtin -outdir /var/tmp/portage/dev-python/m2crypto-0.35.2/work/M2Crypto-0.35.2/M2Crypto -o SWIG/_m2crypto_wrap.c SWIG/_m2crypto.i
/usr/include/bits/types.h:139: Error: CPP #error "". Use the -cpperraswarn option to continue swig processing.
error: command 'swig' failed with exit status 1

I'm going to investigate, as m2crypto is required to setup metatools, which is required for autogenning afaiu.