[Ada] Fix couple of oversights in the implementation of AI12-0128

[Ada] Fix couple of oversights in the implementation of AI12-0128

2019-12-16  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* sem_prag.adb (Atomic_Components): Remove local variable and
	fix consistency issues.  Call Component_Type on the Etype of E.
	(Independent_Components): Remove local variable.
	* sem_util.adb (Is_Subcomponent_Of_Atomic_Object): Properly deal
	with prefixes that are access values.
	* gcc-interface/trans.c (atomic_acces_t): New enumeral type.
	(node_is_atomic) <N_Indexed_Component>: Test the prefix.
	(node_has_volatile_full_access): Rename into...
	(node_is_volatile_full_access): ...this.
	(node_is_component): New predicare.
	(gnat_strip_type_conversion): Delete.
	(outer_atomic_access_required_p): Likewise.
	(atomic_access_required_p): Rename into...
	(get_atomic_access): ...this.  Implement the 3 different semantics
	of Atomic and Volatile_Full_Access.
	(simple_atomic_access_required_p): New predicate.
	(Call_to_gnu): Remove outer_atomic_access parameter and change the
	type of atomic_access parameter to atomic_acces_t.  Replace call to
	atomic_access_required_p with simple_atomic_access_required_p for
	the in direction and call get_atomic_access for the out direction
	instead of [outer_]atomic_access_required_p.
	(lhs_or_actual_p): Constify local variables.
	(present_in_lhs_or_actual_p): Likewise.
	(gnat_to_gnu) <N_Identifier>: Replace call to atomic_access_required_p
	with simple_atomic_access_required_p.
	<N_Explicit_Dereference>: Likewise.
	<N_Indexed_Component>: Likewise.
	<N_Selected_Component>: Likewise.
	<N_Assignment_Statement>: Call get_atomic_access for the name instead
	of [outer_]atomic_access_required_p.  Adjust call to Call_to_gnu.
	<N_Function_Call>: Adjust call to Call_to_gnu.
	(get_controlling_type): Fix typo in comment.

From-SVN: r279427