Allow empty store in gss_acquire_cred_from

There is no reason to deny a zero-length cred store, so don't check
for it in val_acq_cred_args or val_add_cred_args.

(cherry picked from commit 970304b558a360e08d8421ef92245d2df0ac5e49)

https://github.com/krb5/krb5/commit/46c07625eb6235a2c810df229fb9a8a968890d5b
Author: Greg Hudson <ghudson@mit.edu>
Committer: Tom Yu <tlyu@mit.edu>
Commit: 46c07625eb6235a2c810df229fb9a8a968890d5b
Branch: krb5-1.11
 src/lib/gssapi/mechglue/g_acquire_cred.c |   12 ------------
 1 files changed, 0 insertions(+), 12 deletions(-)