ada: Remove unnecessary qualifiers for First/Next list operations

ada: Remove unnecessary qualifiers for First/Next list operations

Code cleanup related to work on expression functions for GNATprove
(which require accessibility checks even when they are not expanded
and thus have no explicit return statements).

gcc/ada/ChangeLog:

	* accessibility.adb (First_Selector): Remove redundant and locally
	inconsistent parenthesis.
	(Check_Return_Construct_Accessibility): Remove qualifier from list
	operation.
	* sem_util.adb (Is_Prim_Of_Abst_Type_With_Nonstatic_CW_Pre_Post):
	Likewise.