kernel for 2.2r4

[Arne Nordmark]

It was suggested to remove all versions except 2.2.19 for the 2.2r4
release, but 2.2.19-sun4u_6 has bug #94477 that reports kernel panic
when starting NFS on sun4u machines. In the change list of 2.2.20pre1
there was an NFS fix for sparc64.

Arne