fix new bugs in save code which broke some games in sneaky ways. fixes apollo justice, although reportedly it was broken for other reasons in previous releases. also might have fixed a regression in tomb raider underworld

git-svn-id: https://svn.code.sf.net/p/desmume/code/trunk@4928 5577840e-afb3-4e59-9ef3-2b7f898b1952
make the engineering around kUninitializedSaveDataValue not so horrible; affects "Daigassou! Band Brothers DX" but not tested (make the slot1comp_mc configure the BackupDevice with the appropriate uninitializedValue since it is a property of the physical backup memory hardware)

git-svn-id: https://svn.code.sf.net/p/desmume/code/trunk@4929 5577840e-afb3-4e59-9ef3-2b7f898b1952