Stop using libafsrpc

Stop using libafsrpc

Instead of using libafsrpc.a in the pthreaded server directories,
use the libtool library variants instead.

Change-Id: I4cdbaf5a060b3e5aa82fb0d79535cb4fdc850bcf
Reviewed-on: http://gerrit.openafs.org/8074
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>