Exporting just the filename requires the caller to know where that file sits.
That's useful for things like e.g. icons where callers may several sets to
chose from but here most callers will just use the default svg provided by
libratbag.
Export that, so that we don't have build-time dependencies in the callers just
for that single path.
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
