SDL2 mixer initialization flags

Defaults to FLAC, MP3 and OGG.

Property definitions

gamnit :: display_linux $ GamnitDisplay :: mix_init_flags
	# SDL2 mixer initialization flags
	#
	# Defaults to FLAC, MP3 and OGG.
	var mix_init_flags: MixInitFlags = mix.flac | mix.mp3 | mix.ogg is lazy, writable
lib/gamnit/display_linux.nit:109,2--112,82