v.io/x/lib/nsync: accommodate very slow machines in CV timeout test
v.io/x/lib/nsync: accommodate very slow machines in CV timeout test

The tests of condition variable timeout are testing that something reacts in a
certain real time, since that;''s what the API does.  Our test machines are
sometimes busy, so the test bounds must be quite loose, since the threadds may
not be scheduled promptly.

Change-Id: I7527a0efe7e764b6fec3c31a6a5766b3d3e7b44b

vanadium/go.lib