chip-independent clock code. 'clock' has been renamed 'mcclock' 'clock'
has been renamed 'mcclock' (since it's a driver for that particular
clock, and since eventually there may be another clock chip driver),
and now attaches via seperate match/attach functions to both TC and ISA.
This removes a whole lot of #ifdefs...
Support for AXPpci CPUs,
Support for AlphaStation 600 CPUs,
new boot block structure, which requires an 'installboot'
program and works a lot like the NetBSD/sparc boot blocks.
cgd