gmu: Add recipe for gmu-0.7.1, a music player based on SDL.

gmu: Add recipe for gmu-0.7.1, a music player based on SDL.

* Added Makefile, which adds an install hook and adds the INCS and
  LIBS variables, due to the way OE handles CFLAGS and LDFLAGS.

* Added unknown.mk, the generic mk file, which replaces the version
  shipped with gmu and fixes compilation in OE.

* Added gmu.desktop, which uses the generic audio-player icon.

* Added two additional files, nanonote.keymap and nanonote.mk which
  are specific to ben-nanonote.

* Added nanonote-lcd-blank.patch which fixes LCD blanking under the
  2.6.36 kernel version for the ben-nanonote target.

* Added set-base-dir.patch which sets proper systemwide directories
  for configuration files and libraries (decoders and frontends).
  gmu normally looks under pwd to find such files, which is extremely
  error-prone.

Signed-off-by: Alex Ferguson <thoughtmonster@gmail.com>
Signed-off-by: Kristoffer Ericson <kristoffer.ericson@gmail.com>