Function nginx::RSA_meth_set_mod_exp

pub unsafe extern "C" fn RSA_meth_set_mod_exp(
    rsa: *mut RSA_METHOD, 
    mod_exp: Option<unsafe extern "C" fn(r0: *mut BIGNUM, I: *const BIGNUM, rsa: *mut RSA, ctx: *mut BN_CTX) -> c_int>
) -> c_int