opendingux: GCW0: Auto-mount SCSI disks (for QEMU)

Problems were reported with the SD card emulation of QEMU for MIPS,
so as a workaround we want to be able to mount harddisk images too.
libmodplug: Added package

Library to play lots of tracker formats (including MOD, S3M, XM) and
also standard MIDI files.

http://modplug-xmms.sourceforge.net/
modplugtools: Added package

Simple command line tools to play music files using libmodplug.

http://modplug-xmms.sourceforge.net/
opendingux: GCW0: defconfig: Enabled libmodplug and modplugtools