2bf1f3f5d0
On Ubuntu 16.04 (Xenial), we have to build mbedTLS from source because the version available from apt, mbedTLS 2.2.1, does not work with the RTMPS implementation in OBS, which requires mbedTLS 2.7 at minimum. This is due to the use of the function mbedtls_ssl_conf_dh_param_bin, which was introduced in mbedTLS 2.7.