This one driver pulls in the installers for each other clock driver,
and invokes each in turn:
* No-Slot Clock
* ROMX
* FujiNet
* DClock
* Cricket!
This requires adding `.ifndef JUMBO` guards in the other drivers for
when they pull in include files (symbols, macros, etc). The other
drivers are adjusted to return with carry clear on successful install,
failure otherwise.
