Hi,
wolfSSL's OpenSSL compatibility layer was designed to make porting into existing OpenSSL applications easier, but is far from complete. It maps roughly the most-used 300 OpenSSL functions to the native wolfSSL API, where OpenSSL has over 4,000 in total.
It sounds like the functions you have listed are related to certificate generation. For an example of how wolfSSL does certificate generation, see ./ctaocrypt/test/test.c, specifically the code inside of the #ifdef WOLFSSL_CERT_GEN define of rsa_test().
wolfSSL doesn't currently support this function. For certificate generation, wolfSSL uses an RsaKey structure, which contains a RSA private key. A private key buffer (in DER format) can be loaded into an RsaKey structure using the RsaPrivateKeyDecode() function.
In OpenSSL, this function lets the application set the X.509 certificate version to use. wolfSSL embedded SSL only supports X.509 V3 certificate generation. As such, this function is not needed with wolfSSL.
When doing certificate generation with wolfSSL, the serial number can be set directly by the user when filling in the "Cert" structure.
d. X509_NAME_add_entry_by_txt
Like the previous function, certificate fields can be set directly by the user when filling in the "Cert" structure.
wolfSSL's equivalent to X509_sign() would be the SignCert() function, with usage shown in rsa_test() of test.c.
Best Regards,
Chris