ICU/APIC cleanup part 6/many.

ICU/APIC cleanup part 6/many.

Move the APIC and ICU vector arrays into the new machine interrupt ABI.

Move the interrupt vector setup and teardown code into the new ABI.

Make FAST_HI the default and remove the #define.

Add a vector control function to the machine interrupt ABI.

Start changing names of globals so we can eventually link both ICU and
APIC interrupt code into the same binary.  Note that 'fastunpend' has not
yet been renamed.