Removing old interrupt count support

[Joerg Sonnenberger <joerg%britannica.bec.de@localhost>]

Hi all,
while working on the sysctl conversion, I found myself wondering whether
it is useful to add a syctl interface for the old interrupt count or
just request that all ports are finally converted to evcnt(9).

The list of ports still declaring intrcnt is:

arm: acorn32, epoc32, hpcarm, shark
m68k: amiga, atari, cesfic, luna68k, mac68k, news68km next68km sun2,
sun3, sun68k, x68k
mips: newsmips
powerpc: bebox, evbppc(OPENBLOCKS266), mvmeppc

Joerg