Play music loops times

The music is plays once if loops == 1 and repeats infinitely if loops == -1.

Property definitions

sdl2 $ Mix :: play_music
	# Play `music` `loops` times
	#
	# The music is plays once if `loops == 1` and repeats infinitely if `loops == -1`.
	fun play_music(music: MixMusic, loops: Int): Bool `{
		return Mix_PlayMusic(music, loops) == 0;
	`}
lib/sdl2/mixer.nit:171,2--176,3