(MESS) modernized the Mac Sound device. [Fabio Priuli]

git-svn-id: svn://dspnet.fr/mame/trunk@23388 749742ba-7341-0410-aadc-df50b521781e
small fix with ext mem write (no game uses it tho)

git-svn-id: svn://dspnet.fr/mame/trunk@23389 749742ba-7341-0410-aadc-df50b521781e