add raw afc file writing function
add raw afc file writing function

This will be needed to be able to write the SysInfoExtended file from
an udev callout without having to assume that it's mounted through fuse,
this feels much safer.

hyperair/libgpod,hyperair/libgpod,hyperair/libgpod,neuschaefer/libgpod,neuschaefer/libgpod,neuschaefer/libgpod,neuschaefer/libgpod,hyperair/libgpod,neuschaefer/libgpod,hyperair/libgpod