Function openssl_sys::BN_generate_prime_ex

pub unsafe extern fn BN_generate_prime_ex(r: *mut BIGNUM,
                                          bits: c_int,
                                          safe: c_int,
                                          add: *mut BIGNUM,
                                          rem: *mut BIGNUM,
                                          cb: *const c_void)
                                          -> c_int