XDR memory management fixes

XDR memory management fixes

Change the xdr_free function so that it matches in signature and
behaviour the xdr_free that is available in other xdr packages, and
update all callers.

Don't use xdr_alloc where the data we're allocating isn't freed by
xdr. The only place where xdr_alloc is required is in server stubs
when filling OUT parameters.

Change-Id: Ice231f163726afc374cb25a89302e3d82fa1e093
Reviewed-on: http://gerrit.openafs.org/1168
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>