c++: Set the outer brace marker for missed cases.

c++: Set the outer brace marker for missed cases.

In some cases, a function might be declared as FUNCTION_NEEDS_BODY_BLOCK
but all the content is contained within that block.  However, poplevel
is currently assuming that such cases would always contain subblocks.

In the case that we do have a body block, but there are no subblocks
then st the outer brace marker on the body block.  This situation occurs
for at least coroutine lambda ramp functions and empty constructors.

gcc/cp/ChangeLog:

	* decl.cc (poplevel): Set BLOCK_OUTER_CURLY_BRACE_P on the
	body block for functions with no subblocks.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>