NS_Emulation: Fail if an unsupported NS provider is chosen

This took me quite some time: Tried to use NS_PROVIDER_FR, but the
code was compiled without support for it.  It just failed silently
without printing any error or ever sending any message on the FR link.

Change-Id: I96475127a2079830b3456a8e288adf4c6c908887

library/NS_Emulation.ttcnpp

@@ -382,6 +382,8 @@ module NS_Emulation {
 			connect(self:NSCP, vc_NSP_FR:NSE);
 			vc_NSP_FR.start(NS_Provider_FR.main(g_nsvc_config, g_config, id));
 #endif
+		} else {
+			Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail, "Unsupported NS provider");
 		}
 
 		f_change_state(NSVC_S_DEAD_BLOCKED);