Avoid unneeded GetMSTGT() calls in cc_mslsa.c

Both lcc_resolve() and lcc_get_principal() were using GetMSTGT()
to fetch a ticket from which to obtain the client principal name
of the credentials cache.  However, that name is contained in
the results of the the cache information query; there is no need
to retrieve a full ticket of any sort to get it.  Since there
may sometimes be difficulties obtaining a TGT when UAC is enabled,
avoid these unneeded calls.

(cherry picked from commit 76a16d2652da483dd7bc95f24257e0f195b833f0)

https://github.com/krb5/krb5/commit/90c0f8850ad9595866b8343a9d489cf148f41ba0
Author: Ben Kaduk <kaduk@mit.edu>
Committer: Tom Yu <tlyu@mit.edu>
Commit: 90c0f8850ad9595866b8343a9d489cf148f41ba0
Branch: krb5-1.13
 src/lib/krb5/ccache/cc_mslsa.c |   62 ++++++++++++++++++---------------------
 1 files changed, 29 insertions(+), 33 deletions(-)