afsio: rewrite using libafscp

afsio: rewrite using libafscp

afsio is a utility for file transfer to and from AFS file space
without the help of the AFS client/cache manager.  Using libafscp,
this (partially rewritten) version of afsio is able to accomplish
(1) authenticated access to an AFS path or FID (an existing
KerberosV ticket is required), (2) fall back on unauthenticated
("anonymous") access if authentication (token acquisition) fails,
and (3) work independtly of the AFS cache manager (afsd need not
be running, though CellServDB and ThisCell are currently required).

issues:
1) libvldbint and libafsint are not compiled pthreaded. we link in
what we need. this should be changed when we are all-pthreaded.
2) venus is not a pthreaded-directory otherwise. same deal:
in an all-pthreaded universe, undo the bodge that we do here.
3) venus is not an all-krb5 directory either. slight ick.

Reviewed-on: http://gerrit.openafs.org/4381
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 94d44d59e3d18f1d450e495a55fdd927e7584948)

Change-Id: Ibe140c58970f1b4f2f9e7f016e55d770f8cdcc09
Reviewed-on: http://gerrit.openafs.org/5383
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>