coroutines : Remove throwing_cleanup marks from the ramp [PR95822].

coroutines : Remove throwing_cleanup marks from the ramp [PR95822].

The FE contains a mechanism for cleaning up return expressions if a
function throws during the execution of cleanups prior to the return.

If the original function has a return value with a non-trivial DTOR
and the body contains a var with a DTOR that might throw, the function
decl is marked "throwing_cleanup".

However, we do not [in the coroutine ramp function, which is
synthesised], use any body var types with DTORs that might throw.

The original body [which will then contain the type with the throwing
DTOR] is transformed into the actor function which only contains void
returns, and is also wrapped in a try-catch block.

So (a) the 'throwing_cleanup' is no longer correct for the ramp and
   (b) we do not need to transfer it to the actor which only contains
       void returns.

gcc/cp/ChangeLog:

	PR c++/95822
	* coroutines.cc (morph_fn_to_coro): Unconditionally remove any
	set throwing_cleanup marker.

gcc/testsuite/ChangeLog:

	PR c++/95822
	* g++.dg/coroutines/pr95822.C: New test.