[krbdev.mit.edu #8737] gss_add_cred() ignores desired_name if creating a new credential

[Greg Hudson via RT]

gss_add_cred() only processes desired_name into an internal name if an 
input cred handle is given.  There is no reason to apply this 
condition, and acquiring a mech cred for the default name instead of 
the caller-provided name is clearly the wrong behavior.

Commit 25ee704e83c2c63d4b5ecd12ea31c1979239041e (ticket 7217) altered 
the code so that an internal name is generated if a cred store is given 
but no input cred handle.

This bug was present in the Solaris mechglue but was fixed in changeset 
191d30c3be82 with bug number 6285582.