coroutines: Update func-params-08.C to suspend three times.

coroutines: Update func-params-08.C to suspend three times.

The awaitable initially committed was returning "always ready"
which meant that the suspension code was not used.  Update
the test to suspend at each co_await, since this exercises more
of the infrastructure.

gcc/testsuite/ChangeLog:

2020-02-28  Iain Sandoe  <iain@sandoe.co.uk>

	* g++.dg/coroutines/torture/func-params-08.C: Update
	to suspend for each co_await operation.