Fix compilation error by moving _z_session_init to the right #if

[clachan]

A compilation error (undefined local_zid symbol) caused when neither Z_UNICAST_TRANSPORT nor Z_MULTICAST_TRANSPORT is defined. This patch fixes it.

[cguimaraes]

I would prefer to move _z_bytes_t local_zid = _z_bytes_empty(); outside the #if instead.

Like the snippet below:

int8_t __z_open_inner(_z_session_t *zn, char *locator, z_whatami_t mode) {
    int8_t ret = _Z_RES_OK;

    _z_bytes_t local_zid = _z_bytes_empty();

#if Z_UNICAST_TRANSPORT == 1 || Z_MULTICAST_TRANSPORT == 1
    ret = _z_session_generate_zid(&local_zid, Z_ZID_LENGTH);
    if (ret == _Z_RES_OK) {
        ret = _z_new_transport(&zn->_tp, &local_zid, locator, mode);
        if (ret != _Z_RES_OK) {
            _z_bytes_clear(&local_zid);
        }
    } else {
        _z_bytes_clear(&local_zid);
    }
#else
    ret = _Z_ERR_TRANSPORT_NOT_AVAILABLE;
#endif

    if (ret == _Z_RES_OK) {
        ret = _z_session_init(zn, &local_zid);
    }

    return ret;
}

[clachan]

I would prefer to move _z_bytes_t local_zid = _z_bytes_empty(); outside the #if instead.

Like the snippet below:

int8_t __z_open_inner(_z_session_t *zn, char *locator, z_whatami_t mode) {
    int8_t ret = _Z_RES_OK;

    _z_bytes_t local_zid = _z_bytes_empty();

#if Z_UNICAST_TRANSPORT == 1 || Z_MULTICAST_TRANSPORT == 1
    ret = _z_session_generate_zid(&local_zid, Z_ZID_LENGTH);
    if (ret == _Z_RES_OK) {
        ret = _z_new_transport(&zn->_tp, &local_zid, locator, mode);
        if (ret != _Z_RES_OK) {
            _z_bytes_clear(&local_zid);
        }
    } else {
        _z_bytes_clear(&local_zid);
    }
#else
    ret = _Z_ERR_TRANSPORT_NOT_AVAILABLE;
#endif

    if (ret == _Z_RES_OK) {
        ret = _z_session_init(zn, &local_zid);
    }

    return ret;
}

Thanks for your comments, and I have updated the patch.
Please review.

[cguimaraes]

LGTM