[Ada] Requires_Cleanup_Actions and N_Protected_Body

[Ada] Requires_Cleanup_Actions and N_Protected_Body

This patch disallows N_Protected_Body from being passed to
Requires_Cleanup_Actions. Protected bodies never need cleanup, and are
never passed to Requires_Cleanup_Actions, which is a good thing, because
it would blow up on Handled_Statement_Sequence, which doesn't exist for
N_Protected_Body.

gcc/ada/

	* exp_util.adb (Requires_Cleanup_Actions): Remove
	N_Protected_Body from the case statement, so that case will be
	covered by "raise Program_Error".