svcrpc: fix gss-proxy xdr decoding oops

commit dc43376c26cef74226174a2394f37f2a3f8a8639 upstream.

Uninitialized stack data was being used as the destination for memcpy's.

Longer term we'll just delete some of this code; all we're doing is
skipping over xdr that we don't care about.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>