Upgrade to the level of 1.6.9

Mostly just the differences between openafs-1.6.7 and openafs-1.6.9.
But there are also some other changes: fs and vos behave like those
of openafs if libcafsosd.so.26 can not be found. Smaller restructuring
in rxosd directory. afsio now will be built twice, the version in venus
uses libafscp but doesn#t support OSD while the one in rxosd is our
old source which supports OSD.