engine: server: always set sv_background to zero on server shutdown rather than on server dll unload

engine/server/sv_game.c

@@ -5135,7 +5135,6 @@ void SV_UnloadProgs( void )
 
 	// now we can unload cvars
 	Cvar_FullSet( "host_gameloaded", "0", FCVAR_READ_ONLY );
-	Cvar_FullSet( "sv_background", "0", FCVAR_READ_ONLY );
 
 	// free entity baselines
 	Z_Free( svs.static_entities );

engine/server/sv_main.c

@@ -1077,6 +1077,9 @@ void SV_Shutdown( const char *finalmsg )
 		return;
 	}
 
+	// don't forget to reset sv_background state
+	Cvar_FullSet( "sv_background", "0", FCVAR_READ_ONLY );
+
 	if( COM_CheckString( finalmsg ))
 		Con_Printf( "%s", finalmsg );