Tighten up error handling in rxgk_crypto.c

Also removes some double-buffering that was not needed.

Change-Id: Ibe87cc8e69776829cffd0c1e7bd4cb5d2d12af10
Tidy up error handling in get_creds()

Change-Id: I38f875252ed01ccf40b5edc0d5a4b6edacf794cc
Tighten up error handling for mic_startparams

Also remove unneeded temporary variable.

Change-Id: I1d95d335141e98ef892dde37b6ebcbad8a84ebea
Tighten up error handling for pack_clientinfo

Always be sure to set the minor status to a reasonable value,
and release the buffer allocated by gss_wrap appropriately.

Change-Id: I5d9b9a8de6e9849e2707302bf2b83a57b3331aae
Tighten up error handling for make_pack_token

Split the two XDR-encoding steps off into separate subroutines and
use an RX error code instead of a fake GSSAPI one.
Don't leak memory from the rx_opaque in the local TokenContainer.

Change-Id: I261d47270c145e1302aad2db195ba6d62ba75b29