Log Message:
Add audio/libgig.

libgig is a C++ library for loading, modifying existing and creating new
Gigasampler (.gig) files and DLS (Downloadable Sounds) Level 1/2 files, KORG
sample based instruments (.KSF and .KMP files), SoundFont v2 (.sf2) files
and AKAI sampler data. The source code package includes a couple of command
line tools based on the library.