I just found out how to convert Self-signed CA.crt to C header using pycert_bearssl.py
python3 pycert_bearssl.py convert <ca.crt> --use-store <ca.crt> --output ca_h.h
Please make sure pycert_bearssl.py in same folder with ca.crt or add correct path
I m not sure it why this C header is only works for TLS v1.2.