add G_GNUC_INTERNAL marker to exported functions
add G_GNUC_INTERNAL marker to exported functions

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