Merge in upstream revision 17375.
This removes tremor's internal ogg code and now uses libogg instead so a bunch of changes are just adjusting to the new api. Also brings in improvements to vorbisfile which fixes FS#10484.
Disabled a lot of unused code in the libogg files and moved some small functions into the ogg.h header so they can be inlined. Some small tweaks to fix warnings.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@28742 a1c6a512-1295-4272-9138-f99709370657
