ccdefname.c: Add a new function krb5_cc_set_default_name(), which is

ccdefname.c: Add a new function krb5_cc_set_default_name(), which is
	used set the default ccname stored in the krb5_context.  All of the
	OS-specific functions to determine the default ccname is moved to this
	function.  The krb5_cc_default_name() function now just reads the
	default ccname from the os_context, and will call
	krb5_cc_set_default_name() to set the default ccname if necessary.

t_std_conf: Added functions to test krb5_cc_default_name and
	krb5_cc_set_default_name().  Fixed the call to krb5_locate_kdc to
	support the new variables added by the Cygnus initial ticket API
	merge.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@11140 dc483132-0cff-0310-8789-dd5450dbe970