WITH_SYSCONS is defined.
- Only define mouse menus and mouse menu items if WITH_MICE is defined.
- Use WITH_SLICES instead of explicit lists of architectures to control
the layout of menus dependent on if slices are used on this arch or not.
- Only include the linux startup option if WITH_LINUX is defined.
- Only include the SVR4 startup option on i386. It doesn't work on sparc64,
and it is debatable that it even works on i386.
- Change the OSF1 startup option to execute configOSF1() instead of just
setting the variable so that /compat/osf1 gets created.
Tested on: i386, alpha, sparc64
Approved by: re