[Ada] Expansion in _postconditions confusing CodePeer

[Ada] Expansion in _postconditions confusing CodePeer

gcc/ada/

	* contracts.adb (Build_Postconditions_Procedure): Remove
	internally generated if statement used to control finalization
	actions.
	* exp_ch6.adb (Add_Return, Expand_Non_Function_Return,
	Expand_Simple_Function_Return): Add if statement around
	_postconditions to control finalization.
	* exp_ch7.adb (Build_Finalizer): Likewise.
	* sem_prag.adb (Find_Related_Declaration_Or_Body): Add case to
	handle Context itself being a handled sequence of statements.