roken: Fix out-of-tree libroken builds

roken: Fix out-of-tree libroken builds

The libroken configuration script is supposed to support using a
libroken which is installed out of the OpenAFS tree, but which isn't
in the standard search paths, by using --with-roken=/path/to/base

This didn't previously work. Fix this so that it works correctly,
and also fix a few problems with libafshcrypto, which assumed that
LDFLAGS_roken would always be -L$(TOP_LIBDIR)

Change-Id: I1219692f601a621e6c08ae26516136ed0cc03845
Reviewed-on: http://gerrit.openafs.org/4096
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>