Fix for crashing in thoop, squash from Osso (nw)

git-svn-id: svn://dspnet.fr/mame/trunk@24545 749742ba-7341-0410-aadc-df50b521781e
Fix harddriv.c, skimaxx.c (nw)

git-svn-id: svn://dspnet.fr/mame/trunk@24546 749742ba-7341-0410-aadc-df50b521781e