Use INC_EXCEPTION_CNTR in TLB-miss statistics gathering only after switching
to a kernel default data capability authorised to access kernel memory.
When installing $epcc at the end of an exception handler, be sure to
update $epcc.offset for any changes to $epc.  This is required as of
CHERI ISAv3, although not currently in CHERI1 due to $epcc.offset and
$epc being different, with the former ignored.  This may help improve
stability for nested kernel exception handling for CheriBSD booted on
the formal-model simulation.