All kernel objects in code shared amongs targets (core, plugins, codecs) should be...

All kernel objects in code shared amongs targets (core, plugins, codecs) should be declared SHAREDBSS_ATTR as any core could potentially touch them even though they seem only to involve threads on one core. The exception is target code for particular CPUs where proper allocation is fixed. playlist.c was a little odd too-- use one mutex for the current playlist and a separate one for created playlists (still pondering the necessity of more than one).

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@29305 a1c6a512-1295-4272-9138-f99709370657