Support setting enabled TLS versions in mod_sofia

Previously if tls-version was set to tlsv1 we supported only TLSv1,
but if it was set to sslv23 we supported all versions of TLS.  This
was a weird incorrectly documented behavior that we hope no one was
relying on.

Now we can pass a comma-separated list of TLS/SSL versions that we
would like to support in tls-version.

FS-5839 --resolve

src/mod/endpoints/mod_sofia/mod_sofia.h

@@ -399,6 +399,14 @@ typedef enum {
 	SOFIA_TRANSPORT_WSS
 } sofia_transport_t;
 
+typedef enum {
+	SOFIA_TLS_VERSION_SSLv2 = (1 << 0),
+	SOFIA_TLS_VERSION_SSLv3 = (1 << 1),
+	SOFIA_TLS_VERSION_TLSv1 = (1 << 2),
+	SOFIA_TLS_VERSION_TLSv1_1 = (1 << 3),
+	SOFIA_TLS_VERSION_TLSv1_2 = (1 << 4),
+} sofia_tls_version_t;
+
 typedef enum {
 	SOFIA_GATEWAY_DOWN,
 	SOFIA_GATEWAY_UP,