Fix up testsuite from recent changes.

Fix up testsuite from recent changes.

(1) Make TESTDIR relative (my directory exceeded 108 chars, breaking sockets)
(2) Make TESTDIR if it doesn't exist
(3) Add dummy xc_domain_getinfo and xc_evtchn_bind_virq for fake libxc
(4) Fix tests broken by b594bb976a743d509f1ffabb5bc698874ab90d8f
(5) domain_cleanup() can be static, as it's not used elsewhere.
(6) With -Werror, "use" unused variable in domain_init() if TESTING
(7) Remove debugging printf on watch without perms.
(8) Loosen timeout in xs_test (valgrind + slow machine == bogus timeouts)

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (authored)
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>