coap_tinydtls.c: Add in coap_get_tls_library_version() function
coap_tinydtls.c: Add in coap_get_tls_library_version() function

Add in coap_get_tls_library_version() for determining TLS build base + version

authmillenon/libcoap,authmillenon/libcoap,authmillenon/libcoap