engine: fix client can use kill command while not connected (#492)

engine/server/sv_client.c

@@ -1894,6 +1894,12 @@ static qboolean SV_Kill_f( sv_client_t *cl )
 	if( !SV_IsValidEdict( cl->edict ))
 		return true;
 	
+	if( cl->state != cs_spawned )
+	{
+		SV_ClientPrintf( cl, "Can't suicide - not connected!\n" );
+		return true;
+	}
+
 	if( cl->edict->v.health <= 0.0f )
 	{
 		SV_ClientPrintf( cl, "Can't suicide - already dead!\n");