routine reads the TOD clock of CIA1 on the C64 and C128. Since systime was a
dummy routine common for all CBMs before, this change adds an individual dummy
routine for all other CBM systems. CBM510/610 do also have a TOD clock, so a
similar function as in the C64 could be used ...
git-svn-id: svn://svn.cc65.org/cc65/trunk@3974 b7a2c559-68d2-44c3-8de9-860c34a00d81