Function EVP_DigestSignInit_ex 

pub unsafe extern "C" fn EVP_DigestSignInit_ex(
    ctx: *mut EVP_MD_CTX,
    pctx: *mut *mut EVP_PKEY_CTX,
    mdname: *const c_char,
    libctx: *mut OSSL_LIB_CTX,
    props: *const c_char,
    pkey: *mut EVP_PKEY,
    params: *const OSSL_PARAM,
) -> c_int