-Cosmetic change in a comparison
-Move fat_dir structure out of dircache stack to RAM. Reduce dircache stack size (max level depth should stay be around 20). This should fix nano2g dircache stkov of FS#10679
-Change the structure returned by readdir_cached to match the one returned by readdir_uncached: remove useless fields to save space and avoid any potential incoherence
-Remove one field from the internal structure used by {opend,read,close}dir_cached because it was mostly redundant.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@24708 a1c6a512-1295-4272-9138-f99709370657