tools/memory-model: Make judgelitmus.sh note timeouts

Currently, judgelitmus.sh treats timeouts (as in the "--timeout" argument)
as "!!! Verification error".  This can be misleading because it is quite
possible that running the test longer would have produced a verification.
This commit therefore changes judgelitmus.sh to check for timeouts and
to report them with "!!! Timeout".

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>