Expand tokens in gss cred store "ccache" value

This is needed so that sshd and such can get make practical use of the
"ccache" key in GSS cred stores.

This commit only changes the store path, not the acquisition path.

tests/gss/check-basic.in

@@ -105,7 +105,8 @@ echo "initial ticket"
 ${kinit} -c ${cache} --password-file=${objdir}/foopassword user@${R} || exitcode=1
 
 echo "copy ccache with gss_store_cred"
-${test_add_store_cred} --default --overwrite --env ${cache} ${cache2} || exit 1
+# Note we test that the ccache used for storing is token-expanded
+${test_add_store_cred} --default --overwrite --env ${cache} "${cache2}%{null}" || exit 1
 ${klist} -c ${cache2} || exit 1
 
 echo "keytab"