Improve the default hal callout and fdi paths
The search path hal uses for its callouts differs on various
platforms. The new path should work on more systems out of the box.
The fdi file now also defaults to a path more likely to work by
git-svn-id: https://gtkpod.svn.sourceforge.net/svnroot/gtkpod/libgpod/trunk@2251 f01d2545-417e-4e96-918e-98f8d0dbbcb6