fixed bug with playing two global game sounds as game element sounds

fixed bug with playing two global game sounds as game element sounds

The two game sounds "game.losing" and "game.sokoban_solving" were
played as playfield position related, game element specific sounds
before (which especially caused problems with "game.losing" being
defined as a loop sound, but which was stopped after a very short
time, because loop sounds have to be regularly re-initiated to keep
playing, which was not the case here).

As a result, the sound effect "game.losing" (an evil laughter after
the player has died) could effectively not be heard anymore after a
game was lost for many years.