[krbdev.mit.edu #3091] add krb5_cc_new_unique()

[Jeffrey Altman via RT]

/*
 * Generates a new unique ccache of `type` in `id'. The supplied
 * `hint' (that can be NULL) is a string that the credential cache
 * type can use to base the name of the credential on, this is to make
 * its easier for the user to differentiate the credentials.
 *
 *  Returns 0 or an error code.
 */

krb5_error_code
krb5_cc_new_unique(krb5_context context, const char *type, 
		   const char *hint, krb5_ccache *id)