net: lengthen arbitrary SetDeadline timeout by a few orders of magnitude
The "someTimeout" constant in the net test is “just to test that
net.Conn implementations don't explode when their SetFooDeadline
methods are called”. It was set to 10 seconds, which is short enough
that it could actually matter on some platforms.
Since the point of the constant is just to make sure methods don't
explode, we should set it to be at least a couple of orders of
magnitude longer than the test: then it is guaranteed not to have any
unintended side-effects.