Ada: Fix function call in object notation incorrectly rejected

Ada: Fix function call in object notation incorrectly rejected

This happens in the name of a procedure call, again when there
is an implicit dereference in this name, and the fix to apply to
Find_Selected_Component is again straightforward:

--- a/gcc/ada/sem_ch8.adb
+++ b/gcc/ada/sem_ch8.adb
@@ -8524,9 +8524,7 @@ package body Sem_Ch8 is
          --  Error if the prefix is procedure or entry, as is P.X

          if Ekind (P_Name) /= E_Function
-           and then
-             (not Is_Overloaded (P)
-               or else Nkind (Parent (N)) = N_Procedure_Call_Statement)
+           and then not Is_Overloaded (P)
          then
             --  Prefix may mention a package that is hidden by a local
             --  declaration: let the user know. Scan the full homonym

But this also changes the diagnostics in illegal cases because they are not
uniform in the procedure, so the change also factors them out so as to make
them uniform, which slightly improves them in the end.

gcc/ada/
	PR ada/113352
	* sem_ch4.adb (Diagnose_Call): Tweak error message.
	* sem_ch8.adb (Find_Selected_Component): Remove bypass for calls
	to procedures in the overloaded overloadable case.  Factor out
	the diagnostics code and invoke it uniformly in this case.

gcc/testsuite/
	* gnat.dg/prefix3.adb: New test.
	* gnat.dg/prefix3_pkg.ads: New helper.
	* gnat.dg/prefix3_pkg.adb: Likewise.